Sweden's Medical Products Agency has released a warning this week that St. John's wort, a commonly used herbal remedy for depression and mood disorders, may block the contraceptive effects of birth control pills.
According to the agency, two women became pregnant while taking both the pill and the herbal supplement. Previous warnings on the negative effects of combining St. John's wort with prescription medications have also been released by nationally run agencies in the United Kingdom, Australia, and the United States, though the U.S. Food and Drug Administration has yet to regulate this over-the-counter supplement.
To find out whether the potentially thousands of American women taking both the pill and St John's wort were at risk for unwanted pregnancies, ABCNEWS.com asked experts in the field to weigh in on the topic:
"Like other non-traditional medical treatments, St. John's wort may interact with other medication or treatments. Unfortunately, since these agents do not undergo the same testing nor the same post-marketing surveillance as FDA-approved pharmaceutical agents, these interactions are often unknown.
A report from the National Institutes of Health suggested an interaction between St. John's wort and antiretroviral drugs [used for treating AIDS]. The supposed mechanism of action was one that would potentially also effect oral contraceptives. However, no studies have been completed yet which give us any specific information about such an interaction.
Until we know more, we recommend to our patients to seriously consider a non-oral method of contraception if they MUST take St. John's wort, primarily because an unwanted pregnancy is a hard way to find out if there really is an interaction. Additionally, if a woman truly needs an antidepressant, we have products which are FDA-approved and known not to interact with oral contraceptives.
More importantly, we stress that being "natural" does not always mean something is good and without unwanted effects (like interacting with other drugs, anesthetics, etc.). After all, cocaine and heroin are natural substances, too. As such, it is important to review all medications and treatments with your health care provider."
— Mitchell Creinin, MD, director of family planning and family planning research in the Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh.
"[Interfering with oral contraceptives] is but one of several serious interactions that are now known and there are many others that are predictable. St. John's wort has caused people to reject transplanted organs when it caused their levels of cyclosporine to fall. AIDS patients have lost control of HIV because St. John's wort caused them to eliminate their protease inhibitors [antiviral drugs] too quickly. Unfortunately about 40 percent of patients refuse to tell their docs that they are taking herbals, even when asked. Most are not asked."
— Raymond L. Woosley, MD, PhD., vice president for health sciences, University of Arizona