Question: why can you not take grapefruit with felodipine

Reference:
 Grapefruit 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. What is it? 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 is commonly taken by mouth for weight loss. It is also used for asthma, high cholesterol, and many other conditions, but there is not good scientific evidence to support these other uses. 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 effective is it? <i>Natural Medicines Comprehensive Database</i> rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.The effectiveness ratings for <b>GRAPEFRUIT</b> are as follows: <h3>Possibly effective for...</h3> /h3> <b>Weight loss</b>. Taking a specific product containing sweet orange, blood orange, and grapefruit extracts seems to decrease body weight and body fat in overweight people. Some research also shows that eating fresh grapefruit daily increases weight loss in overweight people. <h3>Insufficient evidence to rate effectiveness for...</h3> /h3> <b>Asthma</b>. 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.<b>Eczema (atopic dermatitis)</b>. Early research shows that grapefruit seed extract can decrease constipation, gas, and stomach discomfort in people with eczema. This benefit may be due to the effect of grapefruit on intestinal bacteria.<b>High cholesterol</b>. 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.<b>High blood fats called triglycerides</b>. Eating one grapefruit per day appears to reduce total cholesterol, low-density lipoprotein (LDL or "bad") cholesterol, and triglyceride levels in people with high triglyceride levels.<b>Lice</b>. Early research shows that applying a shampoo containing grapefruit extract to the hair of children for 10-20 minutes kills lice. Applying the shampoo again 10 days later helps remove any remaining nits.<b>Depression</b>.<b>Digestive complaints in people with eczema</b>.<b>Hardening of the arteries (atherosclerosis)</b>.<b>Infections</b>.<b>Muscle tiredness</b>.<b>Preventing cancer</b>.<b>Promoting hair growth</b>.<b>Psoriasis</b>.<b>Reducing acne and oily skin</b>.<b>Stress</b>.<b>Treating headaches</b>.<b>Toning the skin</b>.<b>Yeast infections (as a vaginal douche)</b>.<b>Other conditions</b>. More evidence is needed to rate the effectiveness of grapefruit for these uses. How does it 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. Are there safety concerns? Grapefruit is <b>LIKELY SAFE</b> in the amounts normally used as food and <b>POSSIBLY SAFE</b> when taken by mouth for medicinal purposes. Grapefruit is <b>POSSIBLY UNSAFE</b> 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). <h4>Special precautions & warnings:</h4> <b>Pregnancy and breast-feeding</b>: Not enough is known about the use of grapefruit during pregnancy and breast-feeding. Stay on the safe side and avoid use. <b>Breast cancer</b>: 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. <b>Diseases of the heart muscle</b>: Consuming grapefruit juice might increase the potential for abnormal heart rhythm. People with these diseases should consume grapefruit juice in moderation. <b>Hormone sensitive cancers and conditions</b>: 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. Are there interactions with medications? Major Do not take this combination. <b>Amiodarone (Cordarone)</b> 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). <b>Artemether (Artenam, Paluther)</b> 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). <b>Atorvastatin (Lipitor)</b> Atorvastatin (Lipitor) is a type of cholesterol lowering medication known as a "statin." The body breaks down atorvastatin (Lipitor) to get rid of it. Grapefruit juice might decrease how quickly the body breaks down atorvastatin (Lipitor). Drinking grapefruit juice while taking atorvastatin (Lipitor) might increase the effects and side effects of this medication. <b>Buspirone (BuSpar)</b> 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). <b>Carbamazepine (Tegretol)</b> 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). <b>Carvedilol (Coreg)</b> 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). <b>Celiprolol (Celicard)</b> 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. <b>Cisapride (Propulsid)</b> 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). <b>Clomipramine (Anafranil)</b> 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). <b>Clopidogrel (Plavix)</b> 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. <b>Cyclosporine (Neoral, Sandimmune)</b> 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. <b>Dextromethorphan (Robitussin DM, and others)</b> 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). <b>Estrogens</b> 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. <b>Etoposide (VePesid)</b> 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. <b>Halofantrine</b> 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. <b>Lovastatin (Mevacor)</b> Lovastatin (Mevacor) is a type of cholesterol lowering medication known as a "statin." The body breaks down lovastatin (Mevacor) to get rid of it. Grapefruit juice might decrease how quickly the body breaks down lovastatin (Mevacor). Drinking grapefruit juice while taking lovastatin (Mevacor) might increase the effects and side effects of this medication. <b>Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)</b> 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. <b>Medications for high blood pressure (Calcium channel blockers)</b> 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. <b>Medications moved by pumps in cells (Organic anion-transporting polypeptide substrates)</b> 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). <b>Medications used for lowering cholesterol (Statins)</b> The body breaks down certain cholesterol-lowering medicines called "statins" to get rid of them. Grapefruit juice might decrease how quickly the body breaks down "statins". Drinking grapefruit juice while taking certain "statins" might increase the effects and side effects of these medications. Grapefruit seems to decrease how quickly the body breaks down certain "statins" including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor). <b>Methylprednisolone</b> 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. <b>Praziquantel (Biltricide)</b> 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). <b>Quinidine</b> 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. <b>Scopolamine (Transderm Scop)</b> 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. <b>Sedative medications (Benzodiazepines)</b> 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). <b>Sildenafil (Viagra)</b> 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). <b>Simvastatin (Zocor)</b> The body breaks down simvastatin (Zocor) to get rid of it. Grapefruit juice might decrease how quickly the body breaks down simvastatin (Zocor). Drinking grapefruit juice while taking simvastatin (Zocor) might increase the effects and side effects of this medicine. <b>Tacrolimus (Prograf)</b> The body breaks down tacrolimus (Prograf) to get rid of it. Grapefruit can decrease how quickly the body breaks down tacrolimus (Prograf). Eating grapefruit or drinking grapefruit juice while taking tacrolimus (Prograf) can increase the effects and side effects of tacrolimus (Prograf). Avoid eating grapefruit or drinking grapefruit juice if you are taking tacrolimus. <b>Terfenadine (Seldane)</b> 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). <b>Ticagrelor (Brilinta)</b> 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). Moderate Be cautious with this combination. <b>Aliskiren (Tekturna, Rasilez)</b> 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. <b>BUDESONIDE (Pulmicort)</b> 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). <b>Caffeine</b> 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. <b>Colchicine</b> 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. <b>Dapoxetine (Priligy)</b> The body breaks down dapoxetine (Priligy) to get rid of it. Grapefruit juice can decrease how quickly the body gets rid of dapoxetine (Priligy). Taking grapefruit juice along with dapoxetine (Priligy) might increase the effects and side effects of dapoxetine. <b>Erythromycin</b> 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. <b>Fexofenadine (Allegra)</b> 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. <b>Fluvoxamine (Luvox)</b> 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). <b>Itraconazole (Sporanox)</b> 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. <b>Levothyroxine (Synthroid, others)</b> 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. <b>Losartan (Cozaar)</b> 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. <b>Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)</b> 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. <b>Medications changed by the liver (Cytochrome P450 2C19 (CYP2C19) substrates)</b> 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. <b>Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)</b> 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. <b>Methadone (Dolophine)</b> 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). <b>Nadolol (Corgard)</b> 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. <b>Nilotinib (Tasigna)</b> 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). <b>Oxycodone (Oxycontin)</b> 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). <b>Pitavastatin (Livalo)</b> The body breaks down pitavastatin (Livalo) to get rid of it. Grapefruit juice might decrease how quickly the body breaks down pitavastatin (Livalo). Drinking grapefruit juice while taking pitavastatin (Livalo) might increase the effects and side effects of this medicine. <b>Primaquine</b> 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. <b>Saquinavir (Fortovase, Invirase)</b> 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. <b>Sertraline</b> 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. <b>Sunitinib (Sutent)</b> The body breaks down sunitinib (Sutent) to get rid of it. Grapefruit juice might decrease how quickly the body breaks down sunitinib (Sutent). Drinking grapefruit juice while taking sunitinib (Sutent) might 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. <b>Talinolol</b> Grapefruit juice can reduce how much talinolol is available in the body. Drinking grapefruit juice with talinolol might reduce the effects of talinolol. <b>Theophylline</b> Drinking grapefruit juice might decrease the effects of theophylline. There's not enough information to know if this is a big concern. <b>Tolvaptan (Samsca)</b> 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). <b>Warfarin (Coumadin)</b> 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. Minor Be watchful with this combination. <b>Acebutolol (Sectral)</b> 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. <b>Amprenavir (Agenerase)</b> Grapefruit might slightly decrease how much amprenavir (Agenerase) is absorbed by the body. But this interaction is probably not a major concern. Are there interactions with herbs and supplements? <b>Licorice</b> Drinking grapefruit juice when taking licorice might increase licorice's ability to cause potassium depletion. <b>Red yeast</b> Grapefruit (juice or fruit) changes the way the body processes red yeast. Grapefruit can increase the amount of lovastatin from red yeast in the blood. <b>Thunder god vine</b> Thunder god vine contains triptolide. The body breaks down triptolide to get rid of it. Grapefruit can decrease how quickly the body breaks down triptolide. Drinking grapefruit juice while taking thunder god vine containing triptolide might increase the effects and side effects of thunder god vine. Are there interactions with foods? <b>Tonic water</b> Grapefruit might interfere with the way the body processes the quinine that is contained in tonic water. People who have a heart rhythm disorder (long QT syndrome, for example) should avoid taking grapefruit and tonic water together, since that combination might worsen their heart condition. <b>Wine</b> Grapefruit juice might decrease how quickly the liver breaks down some medications. This might increase the side effects of these medications. Adding red wine to the mix can increase these side effects even more. White wine, however, does not seem to interact with grapefruit or medications that are broken down by the liver. What dose is used? The following doses have been studied in scientific research: <b>BY MOUTH:</b> /b> <b>For weight loss</b>: 450-700 mg of a specific product containing sweet orange, blood orange, and grapefruit extracts twice daily for 12 weeks has been used. Eating half a grapefruit three times daily, drinking 8 ounces of grapefruit juice three times daily, or taking capsules containing freeze-dried whole grapefruit 500 mg three times before meals for 12 weeks has also been used. 

Answer: 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.