Stinging nettle (Urtica dioica and Urtica urens) preparations have been used in nursing mothers orally as a postpartum as a "tonic" for treating anemia.[1,2] It is also a purported galactogogue.[2-7] Hypothetically, a galactogogue effect might be due to the binding of sex hormone-binding globulin by polar extracts of Urtica dioica causing elevated serum estrogen levels, by histamine-induced prolactin release, or by serotonin-induced release of thyrotropin-releasing hormone.[8] However, no scientifically valid clinical trials support the safety or efficacy in nursing mothers or infants for any use. Galactogogues should never replace evaluation and counseling on modifiable factors that affect milk production.[9] Although stinging nettle is generally well tolerated in adults, topical use can cause urticaria when applied topically, and application on one mother's nipple resulted in allergic skin rash in her breastfed infant. It is probably best not to apply stinging nettle topically to the breast while breastfeeding.
Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.