Postpartum depression is a relatively common event, affecting 10 to 15% of women after the birth of a child. Many women, however, do not receive treatment, and one of the most common reasons for avoiding or deferring treatment is concern regarding the use of medications while breastfeeding. A preliminary study from Lee and colleagues at the Motherisk Program in Toronto, Canada has investigated the use of St. John’s wort in breastfeeding women.

Women contacting the Montherisk Program regarding the safety of medication usage during breastfeeding were candidates for this prospective, observational cohort study. Thirty-three women who were breastfeeding while taking St. John’s wort were enrolled (Group 1). Two age- and parity-matched control groups consisting of women with depression (Group 2) and women with no depression (Group 3) were also recruited. During a follow-up interview, information was gathered regarding treatment and adverse events.

Among the infants nursed by mothers taking St. John’s wort (Group 1), there were significantly more reports of adverse events, including colic (n=2), drowsiness (n=2), and lethargy (n=1). Although earlier reports in animals suggested that St. John’s wort may reduce milk production, this study did not indicate any differences in milk production (as reported by the mothers) between the three groups. Furthermore, there were no differences in weight gain (as reported by the child’s physician) among infants in the three groups.

While this study indicates that nursing infants exposed to St. John’s wort may be at risk for adverse events, it is reassuring that none of the exposed children required any type of medical intervention. One of the shortcomings of this study, however, is that it did not use blinded raters in its observations of the infants and relied instead on the observations of mothers and their physicians, who were aware of the mother’s medication status. In this situation, adverse events may be over-reported, reflecting anxiety or increased vigilance rather than signifying a real problem. Still the findings should not be dismissed, and the use of St. John’s wort in nursing mothers requires further investigation.

At this point there are more data regarding the use of conventional antidepressants during breastfeeding. Available data on the tricyclic antidepressants, fluoxetine, paroxetine, and sertraline during breastfeeding have been encouraging and indicate a low risk of adverse events in the nursing infant. Pending further information regarding the efficacy of St. John’s wort for postpartum depression and the safety of this herbal preparation in nursing infants, conventional antidepressants, particularly the selective serotonergic reuptake inhibitors, remain the first line of treatment for women with postpartum depression.

Ruta Nonacs, M.D., Ph.D.

Lee A, Minhas R, Matsuda N, Lam M, Ito S. The safety of St. John’s wort (Hypericum perforatum) during breastfeeding. J Clin Psychiatry. 2003 Aug;64(8):966-8.