St. John’s wort, the leading
complementary and alternative treatment for depression in the United States,
can be dangerous when taken with many commonly prescribed drugs, according to a
study by researchers at Wake Forest Baptist Medical Center.
The researchers reported that the herbal supplement can
reduce the concentration of numerous drugs in the body, including oral
contraceptive, blood thinners, cancer chemotherapy and blood pressure
medications, resulting in impaired effectiveness and treatment failure.
“Patients may have a false sense of safety with so-called
‘natural’ treatments like St. John’s wort,” said Sarah Taylor, M.D., assistant
professor of dermatology at Wake Forest Baptist and lead author of the study.
“And it is crucial for physicians to know the dangers of ‘natural’ treatments
and to communicate the risks to patients effectively.”
The study is published in the current online issue of The
Journal of Alternative and Complementary Medicine.
To determine how often S. John’s wort (SJW) was being
prescribed or taken with other medications, the team conducted a retrospective
analysis of nationally representative data collected by the National Ambulatory
Medical Care Survey from 1993 to 2010. The research team found the use of SJW
in potentially harmful combinations in 28 percent of the cases reviewed.
drug interactions can include serotonin syndrome, a potentially fatal condition
that causes high levels
of the chemical serotonin to accumulate in your body, heart disease due to
impaired efficacy of blood pressure medications or unplanned pregnancy due to
contraceptive failure, Taylor said.
of the study are that only medications recorded by the physician were analyzed.
However, she said the rate of SJW interactions may actually be underestimated
because the database did not include patients who were using SJW but did not
tell their doctor.
“Labeling requirements for helpful
supplements such as St. John’s wort need to provide appropriate cautions and
risk information,” Taylor said, adding that France has banned the use of St. John’s wort products and several other
countries, including Japan, the United Kingdom, and Canada, are in the process
of including drug-herb interaction warnings on St. John’s wort products.
“Doctors also need to be
trained to always ask if the patient is taking any supplements, vitamins,
minerals or herbs, especially before prescribing any of the common drugs that
might interact with St. John’s wort.”
Co-authors are Steven
Feldman, M.D., and Scott Davis, M.A., of Wake Forest Baptist.
Funding was provided by
the Center for Dermatology Research at Wake Forest Baptist.