Herb may weaken birth control

Scientists give Wort warning The popular herb St. John's wort, which is taken by many as an antidepressant, might reduce the effectiveness of birth-control pills and other medications, experts warn.

In fact, a wave of St. John's wort "miracle babies" resulting from birth-control pill failure is "likely to happen," says pharmacologist Stephen Piscitelli of the National Institutes of Health in Bethesda, Md.

He led a study, published in a recent issue of the scientific journal The Lancet, that showed drop-offs in drug effectiveness greater than 50% when taken with St. John's wort. Because susceptibility to the herb varies, not everyone will suffer the same interactions as those seen in his study, Piscitelli says.

But the findings prompted the Food and Drug Administration to issue a warning about the herb's interaction with other drugs (www.fda.gov/cder/drug/advisory/stjwort.htm).

Much of the FDA advisory concerns interactions with HIV medications. But the notice warns that the herb might disrupt many prescriptions, including heart disease drugs, some cancer drugs and oral contraceptives.

"The only thing the (St. John's wort) label warned me about was sensitivity to sunlight," says Elizabeth McMahan, 31, of Arlington, Va. Her son, Brendan, was born in January.

McMahan took both oral contraceptives and St. John's wort regularly until she received the results of her pregnancy test last May, she says. "I can't say for certain that caused (my pregnancy), but I was taking both and nothing else."

Consumers spent $141 million nationwide on St. John's wort products in 1999, according to San Francisco-based data firm Spins Inc. More than 10 million women nationwide take birth-control pills.

Experts fear that significant numbers of these women might take St. John's wort for mild depression without telling their physicians.

FDA researchers believe the dietary supplement speeds the liver's processing of drugs and dilutes their effectiveness.

A 1999 study in the Journal of Clinical Pharmacology reported menstrual irregularities caused by St. John's wort in women on the pill. No studies have detected a St. John's wort-inspired pregnancy boom, says Piscitelli, but he adds that no one would have known to make the connection until recently.

What should a woman do?

"Choose either another antidepressant or another contraceptive method," says James Trussell of the Office of Population Research at Princeton University.

St. John's wort purveyors, such as Bayer of Morristown, N.J., note that their labels warn consumers to discuss use of their product with their physicians.

The FDA says it is working with manufacturers of prescription drugs to add the warning.