Does Grapefruit Affect Medication?

Grapefruit seems a harmless enough fruit. Packed with vitamin C, vitamin A and potassium, grapefruit contains few calories and practically no fat. If you don't take any medications, grapefruit makes a healthy breakfast fruit or snack. But grapefruit reacts dangerously with some prescription and over-the-counter medications.

Blocked Drug Metabolization

Grapefruit blocks an enzyme in your body, CYP 3A4, from metabolizing some medications that enter your bloodstream. If you continue to take a medication -- a daily dose of oral contraceptives, for example -- the drug builds up in your body. When a doctor prescribes medication, he sets a dose based on your body's ability to metabolize the drug. With grapefruit in your system, the medication doesn't break down adequately. You may experience accelerated side effects similar to taking an overdose.

Birth Control Pills

Birth control pills are among the many drugs that can prove dangerous when taken with grapefruit in your system. Birth control pills contain estrogen, a hormone that slightly increases your risk of developing blood clots. But if you take birth control pills and grapefruit at the same time, the estrogen builds up in your blood rather than safely undergoing metabolism and exiting your system. If estrogen builds up in your body, your risk of blood clots increases. Blood clots can lead to gangrene and can also cause heart attacks if they travel to your heart or strokes if they travel to your brain.

Lethal Combination

Other medications that react adversely with grapefruit include statin medications for cholesterol, heart medications, sedatives and antihistamines. In October 2005, "The Gazette" newspaper reported that a healthy 29-year-old man died shortly after drinking grapefruit juice and taking an antihistamine. You do not need to drink a lot of grapefruit juice to suffer a dangerous reaction. The combination of 1 cup of grapefruit juice and a single dose of some medications could prove fatal, according to "The Gazette." (See Reference 3 and 4.)

Drug Interactions

In 2006, the "New York Times" reported that the following drugs react adversely with grapefruit: Propulsid, ethinyl estradiol, Norvir, Viracept, DynaCirc, nicardipine, nefedipine, Viagra, Agenerase, Plendil, Halcion, cyclosporine, Nimotop, Zaleplon, Rapamune, Versed, Diazepam, Invirase, Buspar, Sular, Desyrel, Serzone, Seroquel, methylprednisolone, Baycol, Hismanal, loratadine, DynaCirc, Zocor, lovastatin, Seroquel, carbamazepine, Prograf, Lipitor, Plendil, Seldane and Cordarone. Other drugs may also react adversely with grapefruit. If you take any medication, consult your doctor before adding grapefruit to your diet.