St. John's wort (Hypericum perforatum)--is it safe during breastfeeding?

Both doctors and patients often treat postnatal depression with herbal preparations derived from St. John's wort. Because these preparations are available to patients as "natural" over-the-counter drugs for depression, they are popularly assumed to be safe. However, no systematic information exists regarding treatment of postnatal depression, infant's safety or pharmacokinetics of hypericum constituents in human breast milk or infant plasma. A mother with post-natal depression was admitted at our service. Her pharmacist had recommended taking a St. John's wort preparation three times a day (Jarsin 300, Lichtwer Pharma AG, Berlin, Germany). Four breast-milk samples (fore and hind milk) during an 18-hour period were analyzed to measure concentration of hypericin and hyperforin. Only hyperforin is excreted into breast milk at a low level, hyperforin and hypericin (two major active components) were below the lower limit of quantification (BLQ: below lower limit of quantification, LQ hypericin: 0.20 ng/ml, LQ hyperforin: 0.50 ng/ml) in this infant's plasma. No side effects were seen in the mother or infant. Before recommending St John's wort for the treatment of depression to women who breastfeed, long-term studies of outcome in infants are needed.