It is not clear how the oil might work for medicinal uses.
Natural Medicines Comprehensive Database 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 GRAPEFRUIT are as follows:
More evidence is needed to rate the effectiveness of grapefruit for these uses.
BY MOUTH:
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).
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.
Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol (Climara, Vivelle, Estring), and others.
Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.
Some medications for high blood pressure include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.
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).
Grapefruit seems to decrease how quickly the body breaks down certain “statins” including lovastatin (Mevacor), simvastatin (Zocor), and atorvastatin (Lipitor).
Some sedative medications (benzodiazepines) that might interact with grapefruit juice include diazepam (Valium), midazolam (Versed), quazepam (Doral), and triazolam (Halcion).
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.
Some medications that are changed by the liver include omeprazole (Prilosec), lansoprazole (Prevacid), and pantoprazole (Protonix); diazepam (Valium); carisoprodol (Soma); nelfinavir (Viracept); and others.
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.