Grapefruit

Other Name(s):

Bioflavonoid Complex, Bioflavonoid Concentrate, Bioflavonoid Extract, Bioflavonoids, Bioflavonoïdes, Bioflavonoïdes d'grumes, Citrus Bioflavones, Citrus Bioflavonoid, Citrus Bioflavonoid Extract, Citrus Bioflavonoids, Citrus Flavones, Citrus Flavonoids, Citrus Grandis Extract, Citrus paradisi, Citrus Seed Extract, Cold-Pressed Grapefruit Oil, Complexe Bioflavonoïde, Complexe Bioflavonoïde de Pamplemousse, Concentré de Bioflavonoïde, CSE, Expressed Grapefruit Oil, Extrait de Bioflavonoïde, Extrait de Bioflavonoïdes d'Agrumes, Extrait de Graines de Pamplemousse, Extrait de Pamplemousse, Extrait Normalisé de Pamplemousse, Flavonoïdes d'Agrumes, Grapefruit Bioflavonoid Complex, Grapefruit Extract, Grapefruit Oil, Grapefruit Seed Extract, Grapefruit Seed Glycerate, GSE, Huile de Pamplemousse, Huile de Pamplemousse Pressée à Froid, Pamplemousse, Pamplemousse Rose, Paradisapfel, Pink Grapefruit, Pomelo, Red Mexican Grapefruit, Shaddock Oil, Standardized Extract of Grapefruit, Toronja.

Overview

Grapefruit is a citrus fruit. People use the fruit, oil from the peel, and extracts from the seed as medicine. Grapefruit seed extract is processed from grapefruit seeds and pulp obtained as a byproduct from grapefruit juice production. Vegetable glycerin is added to the final product to reduce acidity and bitterness.

Grapefruit juice is used for asthma, high cholesterol, "hardening of the arteries" (atherosclerosis), cancer, improving levels of red blood cells, a skin disease called psoriasis, and for weight loss and obesity. It is also used to reduce stomach complaints in people with eczema (atopic dermatitis).

Grapefruit seed extract is taken by mouth for bacterial, viral, and fungal infections including yeast infections.

Grapefruit oil is applied to the skin for tired muscles, hair growth, toning the skin, and for acne and oily skin. It is also used for the common cold, flu (influenza), and swine flu.

Grapefruit seed extract is applied to the skin as a facial cleanser, first-aid treatment, remedy for mild skin irritations, and as a vaginal douche for vaginal yeast infections (candidiasis). It is also used as an ear or nasal rinse for preventing and treating infections; as a gargle for sore throats; in a shampoo to treat lice; as a dental rinse for preventing gingivitis and promoting healthy gums; and as a breath freshener.

Some people inhale grapefruit vapors to help the body retain water, for headache, stress, and depression. Grapefruit seed extract vapor has also been inhaled for the treatment of lung infections.

In food and beverages, grapefruit is consumed as a fruit, juice, and is used as a flavoring component.

In manufacturing, grapefruit oil and seed extract are used as a fragrance component in soaps and cosmetics; and as a household cleaner for fruits, vegetables, meats, kitchen surfaces, dishes, and others.

In agriculture, grapefruit seed extract is used to kill bacteria and fungus, fight mold growth, kill parasites in animal feeds, preserve food and disinfect water.

It's important to remember that drug interactions with grapefruit juice are well documented. The chemistry of the grapefruit varies by the species, the growing conditions, and the process used to extract the juice. Before adding grapefruit to your diet or your list of natural medicines, check with your healthcare provider if you take medications.

How does work?

Grapefruit is a source of vitamin C, fiber, potassium, pectin, and other nutrients. Some components might have antioxidant effects that might help protect cells from damage or reduce cholesterol.

It is not clear how the oil might work for medicinal uses.

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Uses

Insufficient Evidence to Rate Effectiveness for...

  • Asthma. Some research shows that eating vitamin C-rich citrus fruits, including grapefruit and others, might improve lung function in people with asthma. But other studies have not shown this benefit.
  • Eczema (atopic dermatitis). Early research shows that a grapefruit seed extract (ParaMicrocidin, Allergy Research Group) can decrease constipation, gas, and stomach discomfort in people with eczema. This benefit may be due to the effect of grapefruit on intestinal bacteria.
  • High cholesterol. Early research suggest that taking grapefruit pectin daily for 16 weeks decreases total cholesterol and the ratio of low-density lipoprotein (LDL or "bad") cholesterol to high-density lipoprotein (HDL or "good") cholesterol compared to baseline.
  • High blood fats called triglycerides. Eating one grapefruit per day appears to reduce total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride levels in people with high triglyceride levels.
  • Lice. Early research shows that applying a shampoo containing grapefruit extract (Licatack shampoo) to the hair of children for 10-20 minutes kills lice. Applying the shampoo again 10 days later helps remove any remaining nits (91417).
  • Weight loss. Early research suggests that eating fresh grapefruit daily increases weight loss in overweight people.
  • Hardening of the arteries (atherosclerosis).
  • Preventing cancer.
  • Psoriasis.
  • Muscle tiredness.
  • Promoting hair growth.
  • Toning the skin.
  • Reducing acne and oily skin.
  • Treating headaches.
  • Stress.
  • Depression.
  • Infections.
  • Digestive complaints in people with eczema.
  • Yeast infections (as a vaginal douche).
  • Other conditions.
More evidence is needed to rate the effectiveness of grapefruit for these uses.

Side Effects

Grapefruit is LIKELY SAFE in the amounts normally used as food and POSSIBLY SAFE when taken by mouth for medicinal purposes.

Grapefruit is POSSIBLY UNSAFE when taken by mouth in high amounts. If you take any medications, check with your healthcare provider before adding grapefruit to your diet or using it as a medicine. Grapefruit interacts with a long list of medications (see "Are there any interactions with medications?" below).

Precautions

Pregnancy and breast-feeding: Not enough is known about the use of grapefruit during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Breast cancer: There is concern about the safety of drinking excessive amounts of grapefruit juice. Some research suggests that postmenopausal women who consume a quart or more of grapefruit juice every day have a 25% to 30% increased chance of developing breast cancer. Grapefruit juice decreases how estrogen is broken down in the body and might increase estrogen levels in the body. More research is needed to confirm these findings. Until more is known, avoid drinking excessive amounts of grapefruit juice, especially if you have breast cancer or are at higher than usual risk for developing breast cancer.

Diseases of the heart muscle: Consuming grapefruit juice might increase the potential for abnormal heart rhythm. People with these diseases should consume grapefruit juice in moderation.

Hormone sensitive cancers and conditions: Consuming large amounts of grapefruit might increase hormone levels and therefore increase the risk of hormone sensitive conditions. Women with hormone sensitive conditions should avoid grapefruit.

Interactions


Amiodarone (Cordarone)Interaction Rating: Major Do not take this combination.

Grapefruit juice can increase how much amiodarone (Cordarone) the body absorbs. Drinking grapefruit juice while taking amiodarone (Cordarone) might increase the effects and side effects. Avoid drinking grapefruit juice if you are taking amiodarone (Cordarone).


Artemether (Artenam, Paluther)Interaction Rating: Major Do not take this combination.

The body breaks down artemether (Artenam, Paluther) to get rid of it. Grapefruit juice can decrease how quickly the body breaks down artemether (Artenam, Paluther). Drinking grapefruit juice while taking artemether (Artenam, Paluther) might increase the effects and side effects of artemether (Artenam, Paluther). Do not drink grapefruit juice if you are taking artemether (Artenam, Paluther).


Atorvastatin (Lipitor)Interaction Rating: Major Do not take this combination.

Atorvastatin (Lipitor) is a type of cholesterol lowering medication known as a "statin." The body breaks down some "statins" to get rid of them. Grapefruit juice might decrease how quickly the body breaks down "statins" including atorvastatin (Lipitor). Drinking grapefruit juice while taking atorvastatin (Lipitor) or other "statins" might increase the effects and side effects of these medications.

Grapefruit might interact with some "statins" including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). Grapefruit juice does not interact with other "statins" including pravastatin (Pravachol), fluvastatin (Lescol), and rosuvastatin (Crestor).


Buspirone (BuSpar)Interaction Rating: Major Do not take this combination.

Grapefruit juice might increase how much buspirone (BuSpar) the body absorbs. Drinking grapefruit juice while taking buspirone (BuSpar) might increase the effects and side effects of buspirone (BuSpar).


Carbamazepine (Tegretol)Interaction Rating: Major Do not take this combination.

Grapefruit juice might increase how much carbamazepine (Tegretol) the body absorbs. Drinking grapefruit juice while taking carbamazepine (Tegretol) might increase the effects and side effects of carbamazepine (Tegretol).


Carvedilol (Coreg)Interaction Rating: Major Do not take this combination.

The body breaks down carvedilol (Coreg) to get rid of it. Grapefruit juice seems to decrease how quickly the body breaks down carvedilol (Coreg). Drinking grapefruit juice while taking carvedilol (Coreg) might increase the effects and side effects of carvedilol (Coreg).


Celiprolol (Celicard)Interaction Rating: Major Do not take this combination.

Grapefruit appears to decrease how much celiprolol (Celicard) is absorbed. This might decrease the effectiveness of celiprolol (Celicard). Separating administration of celiprolol (Celicard) and consumption of grapefruit by at least 4 hours.


Cisapride (Propulsid)Interaction Rating: Major Do not take this combination.

Grapefruit juice might decrease how quickly the body gets rid of cisapride (Propulsid). Drinking grapefruit juice while taking cisapride (Propulsid) might increase the effects and side effects of cisapride (Propulsid).


Clomipramine (Anafranil)Interaction Rating: Major Do not take this combination.

The body breaks down clomipramine (Anafranil) to get rid of it. Grapefruit juice might decrease how quickly the body gets rid of clomipramine (Anafranil). Taking grapefruit juice along with clomipramine (Anafranil) might increase the effects and side effects of clomipramine (Anafranil).


Clopidogrel (Plavix)Interaction Rating: Major Do not take this combination.

Clopidogrel (Plavix) is a prodrug. Prodrugs need to be activated by the body to work. Grapefruit appears to decrease how much clopidogrel (Plavix) is activated by the body. This might lead to a decreased efficacy of clopidogrel. Do not take grapefruit with clopidogrel.


Cyclosporine (Neoral, Sandimmune)Interaction Rating: Major Do not take this combination.

Grapefruit might increase how much cyclosporine (Neoral, Sandimmune) the body absorbs. Drinking grapefruit juice while taking cyclosporine (Neoral, Sandimmune) might increase the side effects of cyclosporine.


Dextromethorphan (Robitussin DM, and others)Interaction Rating: Major Do not take this combination.

The body breaks down dextromethorphan (Robitussin DM, others) to get rid of it. Grapefruit might decrease how quickly the body breaks down dextromethorphan (Robitussin DM, others). Drinking grapefruit juice while taking dextromethorphan (Robitussin DM, others) might increase the effects and side effects of dextromethorphan (Robitussin DM, others).


EstrogensInteraction Rating: Major Do not take this combination.

The body breaks down estrogens to get rid of them. Grapefruit juice seems to decrease how quickly the body breaks down estrogens and increase how much estrogen the body absorbs. Drinking grapefruit juice while taking estrogens might increase estrogen levels and side effects associated with estrogen such as breast cancer.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol (Climara, Vivelle, Estring), and others.


Etoposide (VePesid)Interaction Rating: Major Do not take this combination.

Grapefruit might decrease how much etoposide (VePesid) the body absorbs. Drinking grapefruit juice while taking etoposide (VePesid) might decrease the effectiveness of etoposide (VePesid). To avoid this interaction, separate taking this medication from consuming grapefruit by at least 4 hours.


HalofantrineInteraction Rating: Major Do not take this combination.

The body breaks down halofantrine to get rid of it. Grapefruit juice seems to decrease how quickly the body breaks down halofantrine. Drinking grapefruit juice while taking halofantrine might increase halofantrine levels and side effects associated with halofantrine, including abnormal heartbeat.


Lovastatin (Mevacor)Interaction Rating: Major Do not take this combination.

Lovastatin (Mevacor) is a type of cholesterol lowering medication known as a "statin." The body breaks down some "statins" to get rid of them. Grapefruit juice might decrease how quickly the body breaks down "statins" including lovastatin (Mevacor). Drinking grapefruit juice while taking lovastatin (Mevacor) or other "statins" might increase the effects and side effects of these medications.

Grapefruit might interact with some "statins" including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). Grapefruit juice does not interact with other "statins" including pravastatin (Pravachol), fluvastatin (Lescol), and rosuvastatin (Crestor).


Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)Interaction Rating: Major Do not take this combination.

Some medications are changed and broken down by the liver. Grapefruit juice might decrease how quickly the liver breaks down some medications. Drinking grapefruit juice while taking some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking grapefruit, talk to your healthcare provider if you are taking any medications that are changed by the liver.

Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.


Medications for high blood pressure (Calcium channel blockers)Interaction Rating: Major Do not take this combination.

Grapefruit juice might increase how much medication for high blood pressure the body absorbs. Drinking grapefruit juice while taking some medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.


Medications moved by pumps in cells (Organic anion-transporting polypeptide substrates)Interaction Rating: Major Do not take this combination.

Some medications are moved by pumps in cells. Grapefruit might change how these pumps work and decrease how much of some medications get absorbed by the body. This could make these medications less effective. To avoid this interaction, separate taking these medications from consuming grapefruit by at least 4 hours.

Some of these medications that are moved by pumps in cells include bosentan (Tracleer), celiprolol (Celicard, others), etoposide (VePesid), fexofenadine (Allegra), fluoroquinolone antibiotics, glyburide (Micronase, Diabeta), irinotecan (Camptosar), methotrexate, paclitaxel (Taxol), saquinavir (Fortovase, Invirase), rifampin, statins, talinolol, torsemide (Demadex), troglitazone, and valsartan (Diovan).


MethylprednisoloneInteraction Rating: Major Do not take this combination.

The body breaks down methylprednisolone to get rid of it. Grapefruit juice can decrease how quickly the body gets rid of methylprednisolone. Drinking grapefruit juice while taking methylprednisolone might increase the effects and side effects of methylprednisolone.


Pitavastatin (Pravachol)Interaction Rating: Major Do not take this combination.

Pitavastatin (Pravachol) is a type of cholesterol lowering medication known as a "statin." The body breaks down some "statins" to get rid of them. Grapefruit juice might decrease how quickly the body breaks down "statins" including pitavastatin (Pravachol). Drinking grapefruit juice while taking pitavastatin (Pravachol) or other "statins" might increase the effects and side effects of these medications.

Grapefruit might interact with some "statins" including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). Grapefruit juice does not interact with other "statins" including pravastatin (Pravachol), fluvastatin (Lescol), and rosuvastatin (Crestor).


Praziquantel (Biltricide)Interaction Rating: Major Do not take this combination.

The body breaks down praziquantel (Biltricide) to get rid of it. Grapefruit juice can decrease how quickly the body breaks down praziquantel (Biltricide). Drinking grapefruit juice while taking praziquantel (Biltricide) might increase the effects and side effects of praziquantel (Biltricide).


QuinidineInteraction Rating: Major Do not take this combination.

The body breaks down quinidine to get rid of it. Grapefruit juice might decrease how fast the body gets rid of quinidine. Drinking grapefruit juice while taking quinidine might increase the chance of side effects.


Scopolamine (Transderm Scop)Interaction Rating: Major Do not take this combination.

The body breaks down scopolamine to get rid of it. Grapefruit juice can decrease how fast the body breaks down scopolamine. Drinking grapefruit juice while taking scopolamine might increase the effects and side effects of scopolamine.


Sedative medications (Benzodiazepines)Interaction Rating: Major Do not take this combination.

Sedative medications can cause sleepiness and drowsiness. Grapefruit juice can decrease how quickly the body breaks some sedative medications. Drinking grapefruit juice while taking some sedative medications can increase the effects and side effects of some sedative medications.

Some sedative medications (benzodiazepines) that might interact with grapefruit juice include diazepam (Valium), midazolam (Versed), quazepam (Doral), and triazolam (Halcion).


Sildenafil (Viagra)Interaction Rating: Major Do not take this combination.

The body breaks down sildenafil (Viagra) to get rid of it. Grapefruit can decrease how quickly the body breaks down sildenafil (Viagra). Drinking grapefruit juice while taking sildenafil (Viagra) can increase the effects and side effects of sildenafil (Viagra).


Simvastatin (Zocor)Interaction Rating: Major Do not take this combination.

Simvastatin (Zocor) is a type of cholesterol lowering medication known as a "statin." The body breaks down some "statins" to get rid of them. Grapefruit juice might decrease how quickly the body breaks down "statins" including simvastatin (Zocor). Drinking grapefruit juice while taking simvastatin (Zocor) or other "statins" might increase the effects and side effects of these medications.

Grapefruit might interact with some "statins" including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). Grapefruit juice does not interact with other "statins" including pravastatin (Pravachol), fluvastatin (Lescol), and rosuvastatin (Crestor).


Terfenadine (Seldane)Interaction Rating: Major Do not take this combination.

Grapefruit can increase how much terfenadine (Seldane) that the body absorbs. Drinking grapefruit juice while taking terfenadine (Seldane) might increase the effects and side effects of terfenadine (Seldane).


Ticagrelor (Brilinta)Interaction Rating: Major Do not take this combination.

The body breaks down ticagrelor (Brilinta) to get rid of it. Grapefruit can decrease how quickly the body breaks down ticagrelor (Brilinta). Drinking grapefruit juice while taking ticagrelor (Brilinta) can increase the effects and side effects of ticagrelor (Brilinta).


Aliskiren (Tekturna, Rasilez)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Aliskiren (Tekturna, Rasilez) is moved by pumps in cells in the body. Grapefruit might change how these pumps work and decrease how much aliskiren (Tekturna, Rasilez) gets absorbed by the body. This could make this medication less effective. To avoid this interaction, separate taking this medication from consuming grapefruit by at least 4 hours.


BUDESONIDE (Pulmicort)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down budesonide (Pulmicort) to get rid of it. Grapefruit might decease how quickly the body gets rid of budesonide (Pulmicort). Drinking grapefruit while taking budesonide (Pulmicort) might increase the side effects of budesonide (Pulmicort).


CaffeineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Grapefruit might decease how quickly the body gets rid of caffeine. Drinking grapefruit while taking caffeine might increase the side effects of caffeine including jitteriness, headache, and a fast heartbeat.


ColchicineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down colchicine to get rid of it. Grapefruit might decrease how quickly the body gets rid of colchicine. But some research shows that grapefruit does not decrease how quickly the body gets rid of colchicine. Until more is known, follow any instructions on the colchicine label related to intake of grapefruit.


ErythromycinInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down erythromycin to get rid of it. Grapefruit can decrease how quickly the body gets rid of erythromycin. Taking grapefruit juice along with erythromycin might increase the effects and side effects of erythromycin.


Fexofenadine (Allegra)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit might decrease how much fexofenadine (Allegra) the body absorbs. Drinking grapefruit juice while taking fexofenadine (Allegra) might decrease the effectiveness of fexofenadine (Allegra). To avoid this interaction, separate taking this medication from consuming grapefruit by at least 4 hours.


Fluvoxamine (Luvox)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit juice can increase how much fluvoxamine (Luvox) the body absorbs. Drinking grapefruit juice while taking fluvoxamine (Luvox) might increase the effects and side effects of fluvoxamine (Luvox).


Itraconazole (Sporanox)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Itraconazole (Sporanox) is used to treat fungal infections. Grapefruit juice might affect how much itraconazole (Sporanox) the body absorbs. But there is not enough information to know if this interaction is a major concern.


Levothyroxine (Synthroid, others)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Levothyroxine (Synthroid, others) is moved by pumps in cells in the body. Grapefruit might change how these pumps work and decrease how much levothyroxine (Synthroid, others) gets absorbed by the body. This could make this medication less effective. To avoid this interaction, separate taking this medication from consuming grapefruit by at least 4 hours.


Losartan (Cozaar)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The liver activates losartan (Cozaar) to make it work. Grapefruit juice might decrease how quickly the body activates losartan (Cozaar). Drinking grapefruit juice while taking losartan (Cozaar) might decrease the effectiveness of losartan.


Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some medications are changed and broken down by the liver. Grapefruit juice might decrease how quickly the liver breaks down some medications. Taking grapefruit juice along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking grapefruit juice talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include amitriptyline (Elavil), haloperidol (Haldol), ondansetron (Zofran), propranolol (Inderal), theophylline (Theo-Dur, others), verapamil (Calan, Isoptin, others), and others.


Medications changed by the liver (Cytochrome P450 2C19 (CYP2C19) substrates)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some medications are changed and broken down by the liver. Grapefruit juice might decrease how quickly the liver breaks down some medications. Taking grapefruit juice along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking grapefruit juice talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include omeprazole (Prilosec), lansoprazole (Prevacid), and pantoprazole (Protonix); diazepam (Valium); carisoprodol (Soma); nelfinavir (Viracept); and others.


Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some medications are changed and broken down by the liver. Grapefruit juice might decrease how quickly the liver breaks down some medications. Taking grapefruit juice along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking grapefruit juice talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include diclofenac (Cataflam, Voltaren), ibuprofen (Motrin), meloxicam (Mobic), and piroxicam (Feldene); celecoxib (Celebrex); amitriptyline (Elavil); warfarin (Coumadin); glipizide (Glucotrol); losartan (Cozaar); and others.


Methadone (Dolophine)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit juice might increase how much methadone (Dolophine) the body absorbs. Drinking grapefruit juice while taking methadone (Dolophine) might increase the effects and side effects of methadone (Dolophine).


Nadolol (Corgard)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Nadolol (Corgard) is moved by pumps in cells in the body. Grapefruit might change how these pumps work and decrease how much nadolol (Corgard) gets absorbed by the body. This could make this medication less effective. However, some research shows that grapefruit does not affect how much nadolol (Corgard) gets absorbed by the body. Until more is known, follow any instructions on the nadolol (Corgard) label related to intake of grapefruit.


Nilotinib (Tasigna)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit juice can increase how much Nilotinib (Tasigna) the body absorbs. Drinking grapefruit juice while taking Nilotinib (Tasigna) might increase the effects and side effects. Avoid drinking grapefruit juice if you are taking Nilotinib (Tasigna).


Oxycodone (Oxycontin)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down oxycodone (Oxycontin) to get rid of it. Grapefruit juice can decrease how quickly the body breaks down oxycodone (Oxycontin). Drinking grapefruit juice while taking oxycodone (Oxycontin) might increase the effects and side effects of Oxycodone (Oxycontin).


PrimaquineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit juice can increase how much primaquine is available in the body. It is unclear what effects this might have. Be cautious with this combination.


Saquinavir (Fortovase, Invirase)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Drinking grapefruit juice can increase how much saquinavir (Fortovase, Invirase) the body absorbs. Drinking grapefruit juice while taking saquinavir (Fortovase, Invirase) might increase the effects and side effects of saquinavir.


SertralineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down sertraline to get rid of it. Grapefruit can decrease how quickly the body breaks down sertraline. Drinking grapefruit juice while taking sertraline can increase the effects and side effects of sertraline.


Sunitinib (Sutent)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down sunitinib (Sutent) to get rid of it. Grapefruit can decrease how quickly the body breaks down sunitinib (Sutent). Drinking grapefruit juice while taking sunitinib (Sutent) can increase the effects and side effects of sunitinib (Sutent). But some research shows that the effect of grapefruit on sunitinib (Sutent) is not a big concern. Until more is known, follow any instructions on the sunitinib (Sutent) label related to intake of grapefruit.


TacrolimusInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Drinking grapefruit juice might increase the concentration of tacrolimus in the blood. Drinking grapefruit juice while taking tacrolimus might increase the risk for side effects.


TalinololInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Grapefruit juice can reduce how much talinolol is available in the body. Drinking grapefruit juice with talinolol might reduce the effects of talinolol.


TheophyllineInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Drinking grapefruit juice might decrease the effects of theophylline. There's not enough information to know if this is a big concern.


Tolvaptan (Samsca)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down tolvaptan (Samsca) to get rid of it. Grapefruit can decrease how quickly the body breaks down tolvaptan (Samsca). Drinking grapefruit juice while taking tolvaptan (Samsca) can increase the effects and side effects of tolvaptan (Samsca).


Warfarin (Coumadin)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Warfarin (Coumadin) is used to slow blood clotting. Drinking grapefruit juice might increase the effects of warfarin (Coumadin) and increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.


Acebutolol (Sectral)Interaction Rating: Minor Be cautious with this combination.Talk with your health provider.

Acebutolol (Sectral) is moved by pumps in cells in the body. Grapefruit might change how these pumps work and decrease how much acebutolol (Sectral) gets absorbed by the body. This could make this medication less effective. To avoid this interaction, separate taking this medication from consuming grapefruit by at least 4 hours.


Amprenavir (Agenerase)Interaction Rating: Minor Be cautious with this combination.Talk with your health provider.

Grapefruit might slightly decrease how much amprenavir (Agenerase) is absorbed by the body. But this interaction is probably not a major concern.

Dosing

The appropriate dose of grapefruit depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for grapefruit. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

QUESTION

Next to red peppers, you can get the most vitamin C from ________________. See Answer

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References

Ameer, B., Weintraub, R. A., Johnson, J. V., Yost, R. A., and Rouseff, R. L. Flavanone absorption after naringin, hesperidin, and citrus administration. Clin Pharmacol Ther 1996;60(1):34-40. View abstract.

Armanini, D., Calo, L., and Semplicini, A. Pseudohyperaldosteronism: pathogenetic mechanisms. Crit Rev Clin Lab Sci 2003;40(3):295-335. View abstract.

Baekey, P. A., Cerda, J. J., Burgin, C. W., Robbins, F. L., Rice, R. W., and Baumgartner, T. G. Grapefruit pectin inhibits hypercholesterolemia and atherosclerosis in miniature swine. Clin Cardiol 1988;11(9):597-600. View abstract.

Bailey, D. G., Dresser, G. K., Kreeft, J. H., Munoz, C., Freeman, D. J., and Bend, J. R. Grapefruit-felodipine interaction: effect of unprocessed fruit and probable active ingredients. Clin Pharmacol Ther 2000;68(5):468-477. View abstract.

Cerda, J. J., Normann, S. J., Sullivan, M. P., Burgin, C. W., Robbins, F. L., Vathada, S., and Leelachaikul, P. Inhibition of atherosclerosis by dietary pectin in microswine with sustained hypercholesterolemia. Circulation 1994;89(3):1247-1253. View abstract.

Curhan, G. C., Willett, W. C., Rimm, E. B., Spiegelman, D., and Stampfer, M. J. Prospective study of beverage use and the risk of kidney stones. Am J Epidemiol. 2-1-1996;143(3):240-247. View abstract.

Ferdman, R. M., Ong, P. Y., and Church, J. A. Pectin anaphylaxis and possible association with cashew allergy. Ann.Allergy Asthma Immunol. 2006;97(6):759-760. View abstract.

Fujioka, K., Greenway, F., Sheard, J., and Ying, Y. The effects of grapefruit on weight and insulin resistance: relationship to the metabolic syndrome. J Med Food 2006;9(1):49-54. View abstract.

Gorinstein, S., Caspi, A., Libman, I., Lerner, H. T., Huang, D., Leontowicz, H., Leontowicz, M., Tashma, Z., Katrich, E., Feng, S., and Trakhtenberg, S. Red grapefruit positively influences serum triglyceride level in patients suffering from coronary atherosclerosis: studies in vitro and in humans. J Agric Food Chem 3-8-2006;54(5):1887-1892. View abstract.

Guo, L. Q., Chen, Q. Y., Wang, X., Liu, Y. X., Chu, X. M., Cao, X. M., Li, J. H., and Yamazoe, Y. Different roles of pummelo furanocoumarin and cytochrome P450 3A5*3 polymorphism in the fate and action of felodipine. Curr Drug Metab 2007;8(6):623-630. View abstract.

Ionescu G, Kiehl R, Wichmann-Kunz F, and et al. Oral citrus seed extract in atopic eczema: in vitro and in vivo studies on intestinal microflora. J Orthomol Med 1990;5(3):155-157.

Kiani, J. and Imam, S. Z. Medicinal importance of grapefruit juice and its interaction with various drugs. Nutr.J. 2007;6:33. View abstract.

Kumar, A., Teuber, S. S., Naguwa, S., Prindiville, T., and Gershwin, M. E. Eosinophilic gastroenteritis and citrus-induced urticaria. Clin Rev Allergy Immunol 2006;30(1):61-70. View abstract.

McLundie, A. C. Localised palatal tooth surface loss and its treatment with porcelain laminates. Restorative.Dent. 1991;7(2):43-44. View abstract.

Palermo, M., Armanini, D., and Delitala, G. Grapefruit juice inhibits 11beta-hydroxysteroid dehydrogenase in vivo, in man. Clin Endocrinol.(Oxf) 2003;59(1):143-144. View abstract.

Pisarik, P. Blood pressure-lowering effect of adding grapefruit juice to nifedipine and terazosin in a patient with severe renovascular hypertension. Arch Fam.Med 1996;5(7):413-416. View abstract.

Sardi, A., Geda, C., Nerici, L., and Bertello, P. [Rhabdomyolysis and arterial hypertension caused by apparent excess of mineralocorticoids: a case report]. Ann Ital Med Int 2002;17(2):126-129. View abstract.

Trinchieri, A., Lizzano, R., Bernardini, P., Nicola, M., Pozzoni, F., Romano, A. L., Serrago, M. P., and Confalanieri, S. Effect of acute load of grapefruit juice on urinary excretion of citrate and urinary risk factors for renal stone formation. Dig.Liver Dis. 2002;34 Suppl 2:S160-S163. View abstract.

Wangensteen, H., Molden, E., Christensen, H., and Malterud, K. E. Identification of epoxybergamottin as a CYP3A4 inhibitor in grapefruit peel. Eur J Clin Pharmacol 2003;58(10):663-668. View abstract.

Wason, S., DiGiacinto, J. L., and Davis, M. W. Effects of grapefruit and Seville orange juices on the pharmacokinetic properties of colchicine in healthy subjects. Clin Ther 2012;34(10):2161-2173. View abstract.

Abdel-Ghaffar F, Semmler M, Al-Rasheid K, Klimpel S, Mehlhorn H. Efficacy of a grapefruit extract on head lice: a clinical trial. Parasitol Res. 2010 Jan;106(2):445-9. View abstract.

Agri Res Svc: Dr. Duke's phytochemical and ethnobotanical databases. www.ars-grin.gov/duke (Accessed 3 November 1999).

Ameer B, Weintraub RA. Drug interactions with grapefruit juice. Clin Pharmacokinet 1997;33:103-21. View abstract.

Andersen, V., Pedersen, N., Larsen, N. E., Sonne, J., and Larsen, S. Intestinal first pass metabolism of midazolam in liver cirrhosis --effect of grapefruit juice. Br J Clin Pharmacol 2002;54(2):120-124. View abstract.

Ando, H., Tsuruoka, S., Yanagihara, H., Sugimoto, K., Miyata, M., Yamazoe, Y., Takamura, T., Kaneko, S., and Fujimura, A. Effects of grapefruit juice on the pharmacokinetics of pitavastatin and atorvastatin. Br J Clin Pharmacol 2005;60(5):494-497. View abstract.

Bailey DG, Arnold JM, Strong HA, et al. Effect of grapefruit juice and naringin on nisoldipine pharmacokinetics. Clin Pharmacol Ther 1993;54:589-94. View abstract.

Bailey DG, Dresser GK, Bend JR. Bergamottin, lime juice, and red wine as inhibitors of cytochrome P450 3A4 activity: comparison with grapefruit juice. Clin Pharmacol Ther 2003;73:529-37. View abstract.

Bailey DG, Dresser GK, Bend JR. Bergamottin, lime juice, and red wine as inhibitors of cytochrome P450 3A4 activity: comparison with grapefruit juice. Clin Pharmacol Ther 2003;73:529-37 . View abstract.

Bailey DG, Dresser GK, Kreeft JH, et al. Grapefruit juice-felodipine interaction: Effect of segments and an extract from unprocessed fruit. Clin Pharmacol Ther 2000;67:107 (abstract PI-71).

Bailey DG, Dresser GK, Leake BF, Kim RB. Naringin is a major and selective clinical inhibitor of organic anion-transporting polypeptide 1A2 (OATP1A2) in grapefruit juice. Clin Pharmacol Ther 2007; 81:495-502. View abstract.

Bailey DG, Dresser GK, Munoz C, et al. Reduction of fexofenadine bioavailability by fruit juices. Clin Pharmacol Ther 2001;69:P21.

Bailey DG, Dresser GK. Grapefruit juice-lovastatin interaction. Clin Pharmacol Ther 2000;67:690. View abstract.

Bailey DG, Spence JD, Munoz C, Arnold JM. Interaction of citrus juices with felodipine and nifedipine. Lancet 1991;337:268-9. View abstract.

Bailey DG. Fruit juice inhibition of uptake transport: a new type of food-drug interaction. Br J Clin Pharmacol 2010;70:645-55. View abstract.

Bailey, D. G., Arnold, J. M., Bend, J. R., Tran, L. T., and Spence, J. D. Grapefruit juice-felodipine interaction: reproducibility and characterization with the extended release drug formulation. Br J Clin Pharmacol 1995;40(2):135-140. View abstract.

Bailey, D. G., Arnold, J. M., Munoz, C., and Spence, J. D. Grapefruit juice--felodipine interaction: mechanism, predictability, and effect of naringin. Clin Pharmacol Ther 1993;53(6):637-642. View abstract.

Becquemont L, Verstuyft C, Kerb R, et al. Effect of grapefruit juice on digoxin pharmacokinetics in humans. Clin Pharmacol Ther 2001;70:311-6. View abstract.

Benmebarek M, Devaud C, Gex-Fabry M, et al. Effects of grapefruit juice on the pharmacokinetics of the enantiomers of methadone. Clin Pharmacol Ther 2004;76:55-63. View abstract.

Benton, R. E., Honig, P. K., Zamani, K., Cantilena, L. R., and Woosley, R. L. Grapefruit juice alters terfenadine pharmacokinetics, resulting in prolongation of repolarization on the electrocardiogram. Clin Pharmacol Ther 1996;59(4):383-388. View abstract.

Bistrup, C., Nielsen, F. T., Jeppesen, U. E., and Dieperink, H. Effect of grapefruit juice on Sandimmun Neoral absorption among stable renal allograft recipients. Nephrol Dial.Transplant. 2001;16(2):373-377. View abstract.

Butland BK, Fehily AM, Elwood PC. Diet, lung function, and lung function decline in a cohort of 2512 middle aged men. Thorax 2000;55:102-8. View abstract.

Calori-Domingues MA, Fonseca H. Laboratory evaluation of chemical control of aflatoxin production in unshelled peanuts (Arachis hypogaea L.). Food Addit Contam 1995;12:347-50. View abstract.

Carey IM, Strachan DP, Cook DG. Effects of changes in fresh fruit consumption on ventilatory function in healthy British adults. Am J Respir Crit Care Med 1998;158:728-33. View abstract.

Castro N, Jung H, Medina R, et al. Interaction between grapefruit juice and praziquantel in humans. Antimicrob Agents Chemother 2002;46:1614-6. View abstract.

Cerda JJ, Robbins FL, Burgin CW, et al. The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle. Clin Cardiol 1988;11:589-94. View abstract.

Chan WK, Nguyen LT, Miller VP, Harris RZ. Mechanism-based inactivation of human cytochrome P450 3A4 by grapefruit juice and red wine. Life Sci 1998;62:PL135-42. View abstract.

Charbit, B., Becquemont, L., Lepere, B., Peytavin, G., and Funck-Brentano, C. Pharmacokinetic and pharmacodynamic interaction between grapefruit juice and halofantrine. Clin Pharmacol Ther 2002;72(5):514-523. View abstract.

Christensen, H., Asberg, A., Holmboe, A. B., and Berg, K. J. Coadministration of grapefruit juice increases systemic exposure of diltiazem in healthy volunteers. Eur J Clin Pharmacol 2002;58(8):515-520. View abstract.

Clifford, C. P., Adams, D. A., Murray, S., Taylor, G. W., Wilkins, M. R., Boobis, A. R., and Davies, D. S. The cardiac effects of terfenadine after inhibition of its metabolism by grapefruit juice. Eur J Clin Pharmacol 1997;52(4):311-315. View abstract.

Coreg monograph. In: Gillis MC, Ed. Compendium of Pharmaceuticals and Specialities (CPS). 34th ed. Ottawa, Ontario, CAN:Canadian Pharmacists Assn, 1999:395.

Culm-Merdek, K. E., von Moltke, L. L., Gan, L., Horan, K. A., Reynolds, R., Harmatz, J. S., Court MH, and Greenblatt, D. J. Effect of extended exposure to grapefruit juice on cytochrome P450 3A activity in humans: comparison with ritonavir. Clin Pharmacol Ther 2006;79(3):243-254. View abstract.

Cuong, B. T., Binh, V. Q., Dai, B., Duy, D. N., Lovell, C. M., Rieckmann, K. H., and Edstein, M. D. Does gender, food or grapefruit juice alter the pharmacokinetics of primaquine in healthy subjects? Br J Clin Pharmacol 2006;61(6):682-689. View abstract.

Curhan GC, Willett WC, Speizer FE, Stamfer MJ. Beverage use and risk of kidney stones in women. Ann Intern Med 1998;128:534-40. View abstract.

Dahan A, Amidon GL. Grapefruit juice and its constituents augment colchicine intestinal absorption: potential hazardous interaction and the role of p-glycoprotein. Pharm Res. 2009 Apr;26(4):883-92. View abstract.

Damkier P, Hansen LL, Brosen K. Effect of diclofenac, disulfiram, itraconazole, grapefruit juice and erythromycin on the pharmacokinetics of quinidine. Br J Clin Pharmacol 1999;48:829-38. View abstract.

Demarles D, Gillotin C, Bonaventure-Paci S, et al. Single-dose pharmacokinetics of amprenavir coadministered with grapefruit juice. Antimicrob Agents Chemother 2002;46:1589-90. View abstract.

Desta, Z., Kivisto, K. T., Lilja, J. J., Backman, J. T., Soukhova, N., Neuvonen, P. J., and Flockhart, D. A. Stereoselective pharmacokinetics of cisapride in healthy volunteers and the effect of repeated administration of grapefruit juice. Br J Clin Pharmacol 2001;52(4):399-407. View abstract.

Di Marco MP, Edwards DJ, Wainer IW, Ducharme MP. The effect of grapefruit juice and seville orange juice on the pharmacokinetics of dextromethorphan: the role of gut CYP3A and P-glycoprotein. Life Sci 2002;71:1149-60. View abstract.

Dresser GK, Bailey DG, Carruthers SG. Grapefruit juice-felodipine interaction in healthy seniors. Clin Pharmacol Ther 1998;65:(abstract PIII-63).

Dresser GK, Bailey DG, Carruthers SG. Grapefruit juice-felodipine interaction in the elderly. Clin Pharmacol Ther 2000;68:28-34. View abstract.

Dresser GK, Bailey DG, Leake BF, et al. Fruit juices inhibit organic anion transporting polypeptide-mediated drug uptake to decrease the oral availability of fexofenadine. Clin Pharmacol Ther 2002;71:11-20. View abstract.

Dresser GK, Kim RB, Bailey DG. Effect of grapefruit juice volume on the reduction of fexofenadine bioavailability: possible role of organic anion transporting polypeptides. Clin Pharmacol Ther 2005;77:170-7. View abstract.

Dresser GK, Spence JD, Bailey DG. Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition. Clin Pharmacokinet 2000;38:41-57. View abstract.

Ducharme, M. P., Warbasse, L. H., and Edwards, D. J. Disposition of intravenous and oral cyclosporine after administration with grapefruit juice. Clin Pharmacol Ther 1995;57(5):485-491. View abstract.

Ebert U, Oertel R, Kirch W. Influence of grapefruit juice on scopolamine pharmacokinetics and pharmacodynamics in healthy male and female subjects. Int J Clin Pharmacol Ther 2000;38:523-31. View abstract.

Edgar, B., Bailey, D., Bergstrand, R., Johnsson, G., and Regardh, C. G. Acute effects of drinking grapefruit juice on the pharmacokinetics and dynamics of felodipine--and its potential clinical relevance. Eur J Clin Pharmacol 1992;42(3):313-317. View abstract.

Edwards DJ, Fitzsimmons ME, Schuetz EG, et al. 6',7'-Dihydroxybergamottin in grapefruit juice and Seville orange juice: effects on cyclosporine disposition, enterocyte CYP3A4, and P-glycoprotein. Clin Pharmacol Ther 1999;65:237-44. View abstract.

Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182

Erlund I, Meririnne E, Alfthan G, Aro A. Plasma kinetics and urinary excretion of the flavanones naringenin and hesperetin in humans after ingestion of orange juice and grapefruit juice. J Nutr 2001;131:235-41. View abstract.

Evans AM. Influence of dietary components on the gastrointestinal metabolism and transport of drugs. Ther Drug Monit 2000;22:131-6. View abstract.

Farkas D, Oleson LE, Zhao Y, et al. Pomegranate juice does not impair clearance of oral or intravenous midazolam, a probe for cytochrome P450-3A activity: comparison with grapefruit juice. J Clin Pharmacol 2007;47:286-94. View abstract.

Forastiere F, Pistelli R, Sestini P, et al. Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. Thorax 2000;55:283-8. View abstract.

Fuhr U, Muller-Peltzer H, Kern R, et al. Effects of grapefruit juice and smoking on verapamil concentrations in steady state. Eur J Clin Pharmacol 2002;58:45-53. View abstract.

Fuhr U. Drug Interactions with Grapefruit Juice. Drug Saf 1998;18:251-72. View abstract.

Fuhr, U., Maier-Bruggemann, A., Blume, H., Muck, W., Unger, S., Kuhlmann, J., Huschka, C., Zaigler, M., Rietbrock, S., and Staib, A. H. Grapefruit juice increases oral nimodipine bioavailability. Int J Clin Pharmacol Ther 1998;36(3):126-132. View abstract.

Fukazawa I, Uchida N, Uchida E, Yasuhara H. Effects of grapefruit juice on the pharmacokinetics of atorvastatin and pravastatin in Japanese. Br J Clin Pharmacol 2003;57:448-55. View abstract.

Fukuda K, Ohta T, Oshima Y, et al. Specific CYP3A4 inhibitors in grapefruit juice: furocoumarin dimers as components of drug interaction. Pharmacogenetics 1997;7:391-6. View abstract.

Garg SK, Kumar N, Bhargava VK, Prabhakar SK. Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy. Clin Pharmacol Ther 1998;64:286-8. View abstract.

Gaudineau C, Beckerman R, Welbourn S, Auclair K. Inhibition of human P450 enzymes by multiple constituents of the Ginkgo biloba extract. Biochem Biophys Res Comm 2004;318:1072–8. View abstract.

Glaeser, H., Bailey, D. G., Dresser, G. K., Gregor, J. C., Schwarz, U. I., McGrath, J. S., Jolicoeur, E., Lee, W., Leake, B. F., Tirona, R. G., and Kim, R. B. Intestinal drug transporter expression and the impact of grapefruit juice in humans. Clin Pharmacol Ther 2007;81(3):362-370. View abstract.

Goldbart A, Press J, Sofer S, Kapelushnik J. Near fatal acute colchicine intoxication in a child. A case report. Eur J Pediatr. 2000;159(12):895-7. View abstract.

Goosen, T. C., Cillie, D., Bailey, D. G., Yu, C., He, K., Hollenberg, P. F., Woster, P. M., Cohen, L., Williams, J. A., Rheeders, M., and Dijkstra, H. P. Bergamottin contribution to the grapefruit juice-felodipine interaction and disposition in humans. Clin Pharmacol Ther 2004;76(6):607-617. View abstract.

Grapefruit-drug interactions. Available at: www.powernetdesign.com/grapefruit (Accessed 26 September 1999).

Greenblatt DJ, von Moltke LL, Harmatz JS. Time course of recovery of cytochrome P450 3A function after single doses of grapefruit juice. Clin Pharmacol Ther 2003;74:121-29 . View abstract.

Greenblatt DJ. Analysis of drug interactions involving fruit beverages and organic anion-transporting polypeptides. J Clin Pharmacol 2009;49:1403-7. View abstract.

Gross AS, Goh YD, Addison RS, et al. Influence of grapefruit juice on cisapride pharmacokinetics. Clin Pharmacol Ther 1999;65:395-401. View abstract.

Gupta MC, Garg SK, Badyal D, et al. Effect of grapefruit juice on the pharmacokinetics of theophylline in healthy male volunteers. Methods Find Exp Clin Pharmacol 1999;21:679-82. View abstract.

Hashimoto, K., Shirafuji, T., Sekino, H., Matsuoka, O., Sekino, H., Onnagawa, O., Okamoto, T., Kudo, S., and Azuma, J. Interaction of citrus juices with pranidipine, a new 1,4-dihydropyridine calcium antagonist, in healthy subjects. Eur J Clin Pharmacol 1998;54(9-10):753-760. View abstract.

Hatch GE. Asthma, inhaled oxidants, and dietary antioxidants. Am J Clin Nutr 1995;61:625S-30S. View abstract.

He K, Iyer KR, Hayes RN, et al. Inactivation of cytochrome P450 3A4 by bergamottin, a component of grapefruit juice. Chem Res Toxicol 1998;11:252-9. View abstract.

Hermans K, Stockman D, Van den Branden F. Grapefruit and tonic: a deadly combination in a patient with the long QT syndrome. Am J Med 2003;114:511-512.

Ho PC, Ghose K, Saville D, Wanwimolruk S. Effect of grapefruit juice on pharmacokinetics and pharmacodynamics of verapamil enantiomers in healthy volunteers. Eur J Clin Pharmacol 2000;56:693-8. View abstract.

Hollander, A. A., van Rooij, J., Lentjes, G. W., Arbouw, F., van Bree, J. B., Schoemaker, R. C., van Es, L. A., van der Woude, F. J., and Cohen, A. F. The effect of grapefruit juice on cyclosporine and prednisone metabolism in transplant patients. Clin Pharmacol Ther 1995;57(3):318-324. View abstract.

Holmberg MT, Tornio A, Joutsi-Korhonen L, Neuvonen M, Neuvonen PJ, Lassila R, Niemi M, Backman JT. Grapefruit juice markedly increases the plasma concentrations and antiplatelet effects of ticagrelor in healthy subjects. Br J Clin Pharmacol. 2013 Jun;75(6):1488-96. View abstract.

Holmberg MT, Tornio A, Neuvonen M, Neuvonen PJ, Backman JT, Niemi M. Grapefruit juice inhibits the metabolic activation of clopidogrel. Clin Pharmacol Ther. 2014 Mar;95(3):307-13. View abstract.

Hori H, Yoshimura R, Ueda N, et al. Grapefruit juice-fluvoxamine interaction -- is it risky or not? J Clin Psychopharmacol 2003;23:422-4. View abstract.

Hu M, Mak VW, Yin OQ, Chu TT, Tomlinson B. Effects of grapefruit juice and SLCO1B1 388A>G polymorphism on the pharmacokinetics of pitavastatin. Drug Metab Pharmacokinet. 2013;28(2):104-8. View abstract.

Hugen, P. W., Burger, D. M., Koopmans, P. P., Stuart, J. W., Kroon, F. P., van Leusen, R., and Hekster, Y. A. Saquinavir soft-gel capsules (Fortovase) give lower exposure than expected, even after a high-fat breakfast. Pharm World Sci 2002;24(3):83-86. View abstract.

Hukkinen, S. K., Varhe, A., Olkkola, K. T., and Neuvonen, P. J. Plasma concentrations of triazolam are increased by concomitant ingestion of grapefruit juice. Clin Pharmacol Ther 1995;58(2):127-131. View abstract.

Ieiri I, Doi Y, Maeda K, Sasaki T, Kimura M, Hirota T, Chiyoda T, Miyagawa M, Irie S, Iwasaki K, Sugiyama Y. Microdosing clinical study: pharmacokinetic, pharmacogenomic (SLCO2B1), and interaction (grapefruit juice) profiles of celiprolol following the oral microdose and therapeutic dose. J Clin Pharmacol. 2012 Jul;52(7):1078-89. View abstract.

Ioannides-Demos LL, Christophidis N, et al. Dosing implications of a clinical interaction between grapefruit juice and cyclosporine and metabolite concentrations in patients with autoimmune diseases. J Rheumatol 1997;24:49-54. View abstract.

Ionescu G, Kiehl F, Wichmann-Kunz F, et al. Oral citrus seed extract in atopic eczema: in vitro and in vivo studies on intestinal microflora. J Orthomolec Med 1990;5:155-7.

Jetter A, Kinzig-Schippers M, Walchner-Bonjean M, et al. Effects of grapefruit juice on the pharmacokinetics of sildenafil. Clin Pharmacol Ther 2002;71:21-9. View abstract.

Josefsson M, Zackrisson AL, Ahlner J. Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers. Eur J Clin Pharmacol 1996;51:189-93. View abstract.

Kanazawa S, Ohkubo T, Sugawara K. The effects of grapefruit juice on the pharmacokinetics of erythromycin. Eur J Clin Pharmacol 2001;56:799-803. View abstract.

Kantola T, Kivisto KT, Neuvonen PJ, et al. Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid. Clin Pharmacol Ther 1998 63:397-402. View abstract.

Kawakami, M., Suzuki, K., Ishizuka, T., Hidaka, T., Matsuki, Y., and Nakamura, H. Effect of grapefruit juice on pharmacokinetics of itraconazole in healthy subjects. Int J Clin Pharmacol Ther 1998;36(6):306-308. View abstract.

Kivisto, K. T., Lilja, J. J., Backman, J. T., and Neuvonen, P. J. Repeated consumption of grapefruit juice considerably increases plasma concentrations of cisapride. Clin Pharmacol Ther 1999;66(5):448-453. View abstract.

Ku, Y. M., Min, D. I., and Flanigan, M. Effect of grapefruit juice on the pharmacokinetics of microemulsion cyclosporine and its metabolite in healthy volunteers: does the formulation difference matter? J Clin Pharmacol 1998;38(10):959-965. View abstract.

Kupferschmidt HH, Fattinger KE, Ha HR, et al. Grapefruit juice enhances the bioavailability of the HIV protease inhibitor saquinavir in man. Br J Clin Pharmacol 1998;45:355-9. View abstract.

Kupferschmidt, H. H., Ha, H. R., Ziegler, W. H., Meier, P. J., and Krahenbuhl, S. Interaction between grapefruit juice and midazolam in humans. Clin Pharmacol Ther 1995;58(1):20-28. View abstract.

Lee YS, Lorenzo BJ, Koufis T, et al. Grapefruit juice and its flavonoids inhibit 11 beta-hydroxysteroid dehydrogenase. Clin Pharmacol Ther 1996;59:62-71. View abstract.

Lee, A. J., Chan, W. K., Harralson, A. F., Buffum, J., and Bui, B. C. The effects of grapefruit juice on sertraline metabolism: an in vitro and in vivo study. Clin Ther 1999;21(11):1890-1899. View abstract.

Lee, M., Min, D. I., Ku, Y. M., and Flanigan, M. Effect of grapefruit juice on pharmacokinetics of microemulsion cyclosporine in African American subjects compared with Caucasian subjects: does ethnic difference matter? J Clin Pharmacol 2001;41(3):317-323. View abstract.

Libersa, C. C., Brique, S. A., Motte, K. B., Caron, J. F., Guedon-Moreau, L. M., Humbert, L., Vincent, A., Devos, P., and Lhermitte, M. A. Dramatic inhibition of amiodarone metabolism induced by grapefruit juice. Br J Clin Pharmacol 2000;49(4):373-378. View abstract.

Lilja JJ, Kivisto KT, Backman JT, et al. Grapefruit juice substantially increases plasma concentrations of buspirone. Clin Pharmacol Ther 1998;64:655-60. View abstract.

Lilja JJ, Kivisto KT, Backman JT, Neuvonen PJ. Effect of grapefruit juice dose on grapefruit juice-triazolam interaction: repeated consumption prolongs triazolam half-life. Eur J Clin Pharmacol 2000;56:411-5. View abstract.

Lilja JJ, Kivisto KT, Neuvonen PJ. Duration of effect of grapefruit juice on the pharmacokinetics of the CYP3A4 substrate simvastatin. Clin Pharmacol Ther 2000;68:384-90. View abstract.

Lilja JJ, Kivisto KT, Neuvonen PJ. Grapefruit juice increases serum concentrations of atorvastatin and has no effect on pravastatin. Clin Pharmacol Ther 1999;66:118-27. View abstract.

Lilja JJ, Kivisto KT, Neuvonen PJ. Grapefruit juice-simvastatin interaction: effect on serum concentrations of simvastatin, simvastatin acid, and HMG-CoA reductase inhibitors. Clin Pharmacol Ther 1998;64:477-83. View abstract.

Lilja JJ, Raaska K, Neuvonen PJ. Effects of grapefruit juice on the pharmacokinetics of acebutolol. Br J Clin Pharmacol 2005;60:659-63. View abstract.

Lilja, J. J., Laitinen, K., and Neuvonen, P. J. Effects of grapefruit juice on the absorption of levothyroxine. Br J Clin Pharmacol 2005;60(3):337-341. View abstract.

Lilja, J. J., Neuvonen, M., and Neuvonen, P. J. Effects of regular consumption of grapefruit juice on the pharmacokinetics of simvastatin. Br J Clin Pharmacol 2004;58(1):56-60. View abstract.

Lundahl, J., Regardh, C. G., Edgar, B., and Johnsson, G. Effects of grapefruit juice ingestion--pharmacokinetics and haemodynamics of intravenously and orally administered felodipine in healthy men. Eur J Clin Pharmacol 1997;52(2):139-145. View abstract.

Lundahl, J., Regardh, C. G., Edgar, B., and Johnsson, G. Relationship between time of intake of grapefruit juice and its effect on pharmacokinetics and pharmacodynamics of felodipine in healthy subjects. Eur J Clin Pharmacol 1995;49(1-2):61-67. View abstract.

Min, D. I., Ku, Y. M., Geraets, D. R., and Lee, H. Effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of quinidine in healthy volunteers. J Clin Pharmacol 1996;36(5):469-476. View abstract.

Misaka S, Miyazaki N, Yatabe MS, Ono T, Shikama Y, Fukushima T, Kimura J. Pharmacokinetic and pharmacodynamic interaction of nadolol with itraconazole, rifampicin and grapefruit juice in healthy volunteers. J Clin Pharmacol. 2013 Jul;53(7):738-45. View abstract.

Monroe KR, Murphy SP, Kolonel LN, Pike MC. Prospective study of grapefruit intake and risk of breast cancer in postmenopausal women: the Mutliethnic Cohort Study. Br J Cancer 2007;97:440-5. View abstract.

Nieminen TH, Hagelberg NM, Saari TI, Neuvonen M, Neuvonen PJ, Laine K, Olkkola KT. Grapefruit juice enhances the exposure to oral oxycodone. Basic Clin Pharmacol Toxicol. 2010 Oct;107(4):782-8. View abstract.

Odou, P., Ferrari, N., Barthelemy, C., Brique, S., Lhermitte, M., Vincent, A., Libersa, C., and Robert, H. Grapefruit juice-nifedipine interaction: possible involvement of several mechanisms. J Clin Pharm Ther 2005;30(2):153-158. View abstract.

Oesterheld J, Kallepalli BR. Grapefruit juice and clomipramine: shifting metabolitic ratios. J Clin Psychopharmacol 1997;17:62-3.

Offman EM, Freeman DJ, Dresser GK, et al. Cisapride interaction with grapefruit juice and red wine. Clin Pharmacol Ther 2000;67:110 (abstract PI-83).

Ozdemir M, Aktan Y, Boydag BS. Interaction between grapefruit juice and diazepam in humans. Eur J Drug Metab Pharmacokinet 1998;23:55-9. View abstract.

Paine, M. F., Widmer, W. W., Hart, H. L., Pusek, S. N., Beavers, K. L., Criss, A. B., Brown, S. S., Thomas, B. F., and Watkins, P. B. A furanocoumarin-free grapefruit juice establishes furanocoumarins as the mediators of the grapefruit juice-felodipine interaction. Am J Clin Nutr 2006;83(5):1097-1105. View abstract.

Parker RB, Yates CR, Soberman JE, Laizure SC. Effects of grapefruit juice on intestinal P-glycoprotein: evaluation using digoxin in humans. Pharmacotherapy 2003;23:979-87. View abstract.

Penzak SR, Acosta EP, Turner M, et al. Effect of Seville orange juice and grapefruit juice on indinavir pharmacokinetics. J Clin Pharmacol 2002;42:1165-70. View abstract.

Penzak SR, Gubbins PO, Gurley BJ, et al. Grapefruit juice decreases the systemic availability of itraconazole capsules in healthy volunteers. Ther Drug Monit 1999;21:304-9. View abstract.

Peterson JJ, Beecher GR, Bhagwat SA, et al. Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. J Food Comp Anal. 2006;19(2006):S74-S80.

Piccirillo G, Magrì D, Matera S, Magnanti M, Pasquazzi E, Schifano E, Velitti S, Mitra M, Marigliano V, Paroli M, Ghiselli A. Effects of pink grapefruit juice on QT variability in patients with dilated or hypertensive cardiomyopathy and in healthy subjects. Transl Res. 2008 May;151(5):267-72. View abstract.

Potential drug interactions with grapefruit. Pharmacist's Letter / Prescriber's Letter 2007;23(2):230204.

Product information for Cordarone. Wyeth Pharmaceuticals, Inc. Philadelphia, PA 19101. September 2006.

Ranzani MR, Fonseca H. Mycological evaluation of chemically-treated unshelled peanuts. Food Addit Contam 1995;12:343-6. View abstract.

Rashid, J., McKinstry, C., Renwick, A. G., Dirnhuber, M., Waller, D. G., and George, C. F. Quercetin, an in vitro inhibitor of CYP3A, does not contribute to the interaction between nifedipine and grapefruit juice. Br J Clin Pharmacol 1993;36(5):460-463. View abstract.

Rashid, T. J., Martin, U., Clarke, H., Waller, D. G., Renwick, A. G., and George, C. F. Factors affecting the absolute bioavailability of nifedipine. Br J Clin Pharmacol 1995;40(1):51-58. View abstract.

Rau SE, Bend JR, Arnold MO, et al. Grapefruit juice-terfenadine single-dose interaction: magnitude, mechanism, and relevance. Clin Pharmacol Ther 1997 61:401-9. View abstract.

Reif S, Nicolson M, Bisset D, et al. Effect of grapefruit juice intake on etoposide bioavailability. Eur J Clin Pharmacol 2002;58:491-4.. View abstract.

Robbins RC, Martin FG, Roe JM. Ingestion of grapefruit lowers elevated hematocrits in human subjects. Int J Vitam Nutr Res 1988;58:414-7. View abstract.

Rogers JD, Zhao J, Liu L, et al. Grapefruit juice has minimal effects on plasma concentrations of lovastatin-derived 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Clin Pharmacol Ther 1999;66:358-66. View abstract.

Sakamoto S, Sato K, Maitani T, Yamada T. [Analysis of components in natural food additive "grapefruit seed extract" by HPLC and LC/MS]. Eisei Shikenjo Hokoku 1996;:38-42. View abstract.

Schmiedlin-Ren P, Edwards DJ, Fitzsimmons ME, et al. Mechanisms of enhanced oral availability of CYP3A4 substrates by grapefruit constituents. Decreased enterocyte CYP3A4 concentration and mechanism-based inactivation by furanocoumarins. Drug Metab Dispos 1997;25:1228-33. View abstract.

Schubert W, Cullberg G, Edgar B, Hedner T. Inhibition of 17 beta-estradiol metabolism by grapefruit juice in ovariectomized women. Maturitas 1994;20:155-63. View abstract.

Schwartz J, Weiss ST. Relationship between dietary vitamin C intake and pulmonary function in the First National Health and Nutrition Examination Survey (NHANES I). Am J Clin Nutr 1994;59:110-4. View abstract.

Schwarz, U. I., Johnston, P. E., Bailey, D. G., Kim, R. B., Mayo, G., and Milstone, A. Impact of citrus soft drinks relative to grapefruit juice on ciclosporin disposition. Br J Clin Pharmacol 2006;62(4):485-491. View abstract.

Schwarz, U. I., Seemann, D., Oertel, R., Miehlke, S., Kuhlisch, E., Fromm, M. F., Kim, R. B., Bailey, D. G., and Kirch, W. Grapefruit juice ingestion significantly reduces talinolol bioavailability. Clin Pharmacol Ther 2005;77(4):291-301. View abstract.

Seidegård J, Randvall G, Nyberg L, Borgå O. Grapefruit juice interaction with oral budesonide: equal effect on immediate-release and delayed-release formulations. Pharmazie. 2009 Jul;64(7):461-5. View abstract.

Shelton MJ, Wynn HE, Hewitt RG, DiFrancesco R. Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects. J Clin Pharmacol 2001;41:435-42. View abstract.

Shoaf SE, Mallikaarjun S, Bricmont P. Effect of grapefruit juice on the pharmacokinetics of tolvaptan, a non-peptide arginine vasopressin antagonist, in healthy subjects. Eur J Clin Pharmacol. 2012 Feb;68(2):207-11. View abstract.

Sigusch, H., Henschel, L., Kraul, H., Merkel, U., and Hoffmann, A. Lack of effect of grapefruit juice on diltiazem bioavailability in normal subjects. Pharmazie 1994;49(9):675-679. View abstract.

Sigusch, H., Hippius, M., Henschel, L., Kaufmann, K., and Hoffmann, A. Influence of grapefruit juice on the pharmacokinetics of a slow release nifedipine formulation. Pharmazie 1994;49(7):522-524. View abstract.

Soldner A, Christians U, Susanto M, et al. Grapefruit juice activates P-glycoprotein-mediated drug transport. Pharm Res 1999;16:478-85. View abstract.

Soons, P. A., Vogels, B. A., Roosemalen, M. C., Schoemaker, H. C., Uchida, E., Edgar, B., Lundahl, J., Cohen, A. F., and Breimer, D. D. Grapefruit juice and cimetidine inhibit stereoselective metabolism of nitrendipine in humans. Clin Pharmacol Ther 1991;50(4):394-403. View abstract.

Sugimoto, K., Araki, N., Ohmori, M., Harada, K., Cui, Y., Tsuruoka, S., Kawaguchi, A., and Fujimura, A. Interaction between grapefruit juice and hypnotic drugs: comparison of triazolam and quazepam. Eur J Clin Pharmacol 2006;62(3):209-215. View abstract.

Sullivan DM, Ford MA, Boyden TW. Grapefruit juice and the response to warfarin. Am J Health-Syst Pharm 1998;55:1581-3. View abstract.

Takanaga H, Ohnishi A, Matsuo H, et al. Pharmacokinetic analysis of felodipine-grapefruit juice interaction based on an irreversible enzyme inhibition model. Br J Clin Pharmacol 2000;49:49-58. View abstract.

Takanaga H, Ohnishi A, Murakami H, et al. Relationship between time after intake of grapefruit juice and the effect on pharmacokinetics and pharmacodynamics of nisoldipine in healthy subjects. Clin Pharmacol Ther 2000:67:201-14. View abstract.

Tanaka S, Uchida S, Miyakawa S, Inui N, Takeuchi K, Watanabe H, Namiki N. Comparison of inhibitory duration of grapefruit juice on organic anion-transporting polypeptide and cytochrome P450 3A4. Biol Pharm Bull. 2013;36(12):1936-41. View abstract.

Tapaninen T, Neuvonen PJ, Niemi M. Grapefruit juice greatly reduces the plasma concentrations of the OATP2B1 and CYP3A4 substrate aliskiren. Clin Pharmacol Ther. 2010 Sep;88(3):339-42. View abstract.

Troisi RJ, Willett WC, Weiss ST, et al. A prospective study of diet and adult-onset asthma. Am J Respir Crit Care Med 1995;151:1401-8. View abstract.

Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;18:2273-81. View abstract.

Uno T, Ohkubo T, Sugawara K, et al. Effects of grapefruit juice on the stereoselective disposition of nicardipine in humans: evidence for dominant presystemic elimination at the gut site. Eur J Clin Pharmacol 2000;56:643-9. View abstract.

Uno, T., Ohkubo, T., Motomura, S., and Sugawara, K. Effect of grapefruit juice on the disposition of manidipine enantiomers in healthy subjects. Br J Clin Pharmacol 2006;61(5):533-537. View abstract.

van Agtmael MA, Gupta V, van der Graaf CA, van Boxtel CJ. The effect of grapefruit juice on the time-dependent decline of artemether plasma levels in healthy subjects. Clin Pharmacol Ther 1999;66:408-14. View abstract.

van Agtmael MA, Gupta V, van der Wosten TH, et al. Grapefruit juice increases the bioavailability of artemether. Eur J Clin Pharmacol 1999;55:405-10. View abstract.

van Erp NP, Baker SD, Zandvliet AS, Ploeger BA, den Hollander M, Chen Z, den Hartigh J, König-Quartel JM, Guchelaar HJ, Gelderblom H. Marginal increase of sunitinib exposure by grapefruit juice. Cancer Chemother Pharmacol. 2011 Mar;67(3):695-703. View abstract.

Varis T, Kivisto KT, Neuvonen PJ. Grapefruit juice can increase the plasma concentration of methylprednisolone. Eur J Clin Pharmacol 2000;56:489-93. View abstract.

Veronese M, Burke J, Dorval E, et al. Grapefruit juice (GFJ) inhibits hepatic and intestinal CYP3A4 dose-dependently. Clin Pharmacol Ther 2000;67:151 (abstract PIII-37).

Veronese ML, Gillen LP, Burke JP, et al. Exposure-dependent inhibition of intestinal and hepatic CYP3A4 in vivo by grapefruit juice. J Clin Pharmacol 2003;43:831-9. . View abstract.

Von Woedtke T, Schluter B, Pflegel P, et al. Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained. Pharmazie 1999;54:452-6. View abstract.

Weber A, Jager R, Borner A, et al. Can grapefruit juice influence ethinylestradiol bioavailability? Contraception 1996;53:41-7. View abstract.

Xiao YJ, Hu M, Tomlinson B. Effects of grapefruit juice on cortisol metabolism in healthy male Chinese subjects. Food Chem Toxicol. 2014 Dec;74:85-90. View abstract.

Xiong H, Li Y, Slavik MF, Walker JT. Spraying chicken skin with selected chemicals to reduce attached Salmonella typhimurium. J Food Prot 1998;61:272-5. View abstract.

Yasui N, Kondo T, Furukori H, et al. Effects of repeated ingestion of grapefruit juice on the single and multiple oral-dose pharmacokinetics and pharmacodynamics of alprazolam. Psychopharmacology (Berl) 2000;150:185-90. View abstract.

Yee, G. C., Stanley, D. L., Pessa, L. J., Dalla, Costa T., Beltz, S. E., Ruiz, J., and Lowenthal, D. T. Effect of grapefruit juice on blood cyclosporin concentration. Lancet 4-15-1995;345(8955):955-956. View abstract.

Yin OQ, Gallagher N, Li A, et al. Effect of grapefruit juice on the pharmacokinetics of nilotinib in healthy participants. J Clin Pharmacol 2010;50:188-94. View abstract.

Zaidenstein R, Avni B, Dishi V, et al. Effect of grapefruit juice on the pharmacokinetics of losartan in healthy volunteers. Clin Pharmacol Ther 1998;65:(abstract PI-60).

Zaidenstein R, Dishi V, Gips M, et al. The effect of grapefruit juice on the pharmacokinetics of orally administered verapamil. Eur J Clin Pharmacol 1998;54:337-40. View abstract.

Zhang YD, Lorenzo B, Reidenberg MM. Inhibition of 11 beta hydroxysteroid dehydrogenase obtained from guinea pig kidney by furosemide, naringenin and some other compounds. J Steroid Biochem Mol Biol 1994;49:81-5. View abstract.

Zitron E, Scholz E, Owen RW, et al. QTc prolongation by grapefruit juice and its potential pharmacological basis: HERG channel blockade by flavonoids. Circulation 2005;835:835-8. View abstract.