What Bad Effects Come From Eating Grapefruit?

Grapefruit is packed with potassium, fiber and vitamin C. The American Heart Association bestowed its heart check on the citrus fruit because of all the nutritious and healthy nutrients it contains. But grapefruit can also erode dental enamel, react dangerously with some medications and may increase the risk of developing breast cancer in post-menopausal women.

Drug Interactions

Grapefruit interacts adversely with many medications because it stops your body's CYP34A enzyme from metabolizing drugs. This means you could end up with too much medication in your system, heightening the likelihood and severity of side effects. Medications known to cause serious side effects when combined with grapefruit include calcium channel blockers, prescribed for heart-related problems; statins, prescribed for high cholesterol; some antidepressants; anti-anxiety and other psychiatric drugs; and immunosuppressants, used to prevent the body's rejection of organ transplants. For a full list of drugs that interact adversely with grapefruit, consult your doctor or pharmacist.

Birth Control Pills

Oral contraceptives, one of the top two methods of birth control used by women since 1962, can cause dangerous interactions when combined with grapefruit. Taking "the Pill" without grapefruit marginally increases your chance of developing blood clots. Taking oral contraceptives with grapefruit magnifies your risk -- the estrogen in the birth control pill stays in your system longer than it should. Blood clots can lead to gangrene, strokes and heart attacks.

Antihistamines

The antihistamines Seldane and Hismanal, both of which are no longer available in the United States, can cause detrimental side effects when combined with grapefruit. A healthy 29-year-old man died of cardiac arrest after taking a dose of Seldane with two glasses of grapefruit juice. Not all antihistamines pose apparent risks. But many drugs of all sorts remain unstudied for their interactions with grapefruit, and warnings about adverse reactions stem more from reported incidents than careful research.

Breast Cancer

A study published in a July 2007 edition of the "British Journal of Cancer," conducted by researchers at the University of Southern California and University of Hawaii, reports that grapefruit could increase post-menopausal women's chances of developing breast cancer by 30 percent. Grapefruit can elevate the level of estrogen in a woman's blood, increasing her risk of developing breast cancer. Catherine Collins, head dietitian from St. George's Hospital in London, says that just because grapefruit can boost a post-menopausal woman's estrogen levels does not necessarily make it dangerous. She says grapefruit could act as a hormone replacement therapy and help alleviate symptoms of menopause.