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
"This is an expected action of St. John's wort. It acts as an inducer of CYP3A4, the enzyme responsible for the metabolism [break down] of estrogens and progestins found in oral contraceptives. Because of the known properties of St. John's wort as an inducer of CYP3A4 and the metabolism of estrogens by CYP3A4, we have included a warning about the potential for unwanted pregnancies when St. John's wort is taken with oral contraceptives in our drug interaction writings for over a year.
When we speak to physician groups about drug interactions, we always include a warning about this potential interaction and the risk of "unwanted birth." This represents a real medical-legal risk to physicians who are asked if St. John's wort is "OK" to take by women taking oral contraceptives. Obviously the answer is NO!"
— John Horn, PharmD, professor of pharmacy, University of Washington
"In my teaching on herbal remedies, I emphasize that the tide of public opinion is flowing in the opposite direction than originally. Remember when St. John's wort was flying off the shelves of health food stores? Then came the "bad news" about St. John's.
Two patients reportedly almost lost their transplanted hearts because St. John's apparently caused the levels of the anti-rejection drug cyclosporine to go down in the blood. Then we learned that St. John's apparently lowers the levels of the protease inhibitors [antiviral drugs] in the body. One by one, more drugs were making the interaction list, including the oral contraceptives.
The Clinical Pharmacology by Gold Standard Multimedia says:
'St. John's wort, Hypericum perforatum, appears to interact with estrogens and oral contraceptives. One report noted intermenstrual bleeding after the concurrent use of St. John's wort in 8 premenstrual women who had been on oral contraceptives for long durations of time. Intermenstrual bleeding implies that there may be a loss of contraceptive or hormonal-replacement efficacy. It is thought that St. John's wort induces hormone metabolism via induction of the hepatic CYP3A4 isoenzyme. It is possible that, as with other CYP3A4 inducers, St. John's wort could also reduce the therapeutic efficacy of progestin-only contraceptives (e.g., levonorgestrel, medroxyprogesterone, and norgestrel). Women should report irregular menstrual bleeding or other hormone-related symptoms to their health care providers if they are taking St. John's wort concurrently with their hormones. Avoidance of these combinations is recommended.'"
— Paul L. Doering, MS, distinguished service professor of Pharmacy Practice, College of Pharmacy, University of Florida-Gainesville
"Although this effect is not common it is certainly pertinent to the US population and should not be dismissed lightly. Unfortunately the herbal medicines lobby and lack of FDA jurisdiction over these herbal medicines has completely prevented any precautionary labeling in the U.S."
— Steve Hall, PhD, professor of medicine, pharmacology and toxicology Indiana University School of Medicine
"No scientific studies support this putative association between St. John's wort and accidental pregnancies in pill users. This is all theoretical. Given that 7 to 8 percent of all pill users will have an accidental pregnancy in the first year of use, and given the large number of women using St. John's wort, a substantial number of pregnancies would be expected in women taking both, even without any biological association."
— David Grimes, MD, vice president of biomedical affairs, Family Health International
"I do not know of such cases, but it is yet another example of the problem of assuming that these herbals are safe? we have no control over their dose, nor knowledge about what the dose should be to be effective, what the side effects are, nor what the possible drug interactions are."
— Brian L. Strom, MD, MPH, chair of the department of biostatistics and epidemiology and director of the Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine