OBJECTIVES: Despite popular and historical use, there has been little modern research conducted to determine the safety and efficacy of herb use during breastfeeding. The purpose of this study was to systematically review the clinical literature on herbal medicine and lactation.

METHODS: The databases PubMed, CAB Abstracts, Cochrane Central Register of Controlled Trials, HealthSTAR, Cumulative Index to Nursing and Allied Health Literature, and Reprotox were systematically searched for human trials from 1970 until 2010. Reference lists from relevant articles were hand-searched.

RESULTS: Thirty-two studies met the inclusion criteria. Clinical studies were divided into three categories: survey studies (n=11), safety studies (n=8), and efficacy studies (n=13). Six studies were randomized controlled trials. The most common herbs studied were St. John's wort (Hypericum perforatum L.) (n=3), garlic (Allium sativum L.) extract (n=2), and senna (Cassia senna L.) (n=2). Studies were very heterogeneous with regard to study design, herbal intervention, and outcome measures. Overall, poor methodological quality predominated among the studies.

CONCLUSIONS: Our review concludes that further research is needed to assess the prevalence, efficacy, and safety of commonly used herbs during breastfeeding.