St. John’s Wort Safety Concerns
St. John’s wort (hypericum perforatum) is one of the five best-selling
herbs in the United States. It is used by many to treat the symptoms of
depression, and many prefer it to prescription medications such as
Paxil® and Zoloft.
However, the herb has been the subject of growing
concern about its interaction with birth control pills, the blood
thinner warfarin, and cyclosporin, a medication used with those who
have received organ transplants. A new study examining its effect on
pregnant women and those who are breastfeeding contributes to the
evidence that the product should be used with caution.
A New Study
The new study, entitled “St. John’s Wort (hypericum perforatum):
Is It Safe During Pregnancy, Breastfeeding and With Prescription
Medications? A Systematic Review,” will soon be published in the
Canadian Journal of Clinical Pharmacology. It is one in a series that
systematically reviews the evidence relating to the safety of herbs
commonly used during pregnancy and lactation.
The study was conducted by a team of Canadian researchers consisting of
the principal investigator Jean Jacques Dugoua, ND, MSc (Cand.),
University of Toronto, Sick Kids Hospital, Toronto Western Hospital,
Truestar Health and Wellness Clinic, and the Canadian College of
Naturopathic Medicine, Toronto, CN; and co-investigators Edward Mills,
DPH, MSc., PhD (Cand.), Department of Epidemiology and Biostatistics,
McMaster University, Ontario, CN; Dan Perri, MD, BscPharm, FRCP(C),
Department of Clinical Pharmacology and Toxicology, University of
Toronto, Toronto, CN; and Gideon Koren, MD, The Motherisk Program,
Hospital for Sick Children, University of Toronto, Toronto, CN.
Dr. Dugoua is presenting the team’s findings at the 21st Annual Meeting of the American Association of Naturopathic Physicians (http://www.Naturopathic.org), being held August 9-12, 2006 at the Oregon Convention Center, Portland, OR.
Methodology
The aim of the study was to systematically review the literature for
evidence on the use, safety, and pharmacology of St. John’s wort
focusing on issues pertaining to pregnancy and lactation. The
investigators searched seven databases for reports relating to the
herb. The databases included AMED, CINAHL, Cochrane CENTRAL, Cochrane
Library, MedLine, Natural Database, and Natural Standard. Each database
was examined in duplicate for data from its inception. Unpublished
research and bibliographies were also included. Data were compiled
according to the grade of evidence found.
Results
The researchers found varying levels of scientific evidence on the
efficacy of use for different conditions; low-level evidence of harm
during pregnancy; and strong evidence of side effects during lactation.
As St. John’s wort interacts with a number of medications due to its
effect on cytochrome P450 enzymes, this may account for some of the
findings.
Conclusions
The researchers concluded:
– Caution is warranted when using St. John’s wort during pregnancy and lactation.
– St. John’s wort may interact with medications prescribed during pregnancy.
– During pregnancy, a case study and some animal studies reported lower birth weights with use of St. John’s wort.
– Strong scientific evidence showed that St. John’s wort consumption
during lactation did not affect maternal milk production nor affect
infant weight, but may cause colic, drowsiness or lethargy.
– St. John’s wort showed strong scientific evidence of being an
effective aid in combating mild to moderate depression and low-level
evidence for other conditions.
Recommendations
The authors urge women not to assume that because herbs are labeled
“natural” that they are safe. They recommend all pregnant and lactating
women consult a licensed, health care professional before consuming any
herb or medicine in general, and St. John’s wort in particular.
Finally, they recommend that any woman experiencing depression let
their physician know immediately.