The majority of studies looking at the safety of St. John's wort while breastfeeding have primarily focused on older infants, rather than those in the first 2 months of life when they are more vulnerable to adverse reactions. One study found that breastfed infants whose mothers were taking St. John's wort showed a slightly increased incidence of colic, drowsiness, and lethargy. However, these effects were not severe and did not require any medical attention.[1]
Another study showed that hypericin and hyperforin in HP are excreted only in limited and non-significant amounts in breast milk.[1]
Furthermore, conflicting information exists regarding whether HP can reduce serum prolactin levels or maternal milk supply.[1]
Because HP is sometimes recommended by midwives for postpartum depression, more research must be conducted to thoroughly assess the safety of using HP during lactation.