Minoxidil was originally designed as a blood pressure tablet, but it was found that a side effect was to promote hair growth. It is now marketed as a topical solution to promote hair growth under the brand name Regaine™ amongst others. It is applied twice daily to affected areas of the scalp.
If topical minoxidil is used, accidental exposure of babies should be avoided by contact with hair, regardless of infant feeding status.
I have had several questions recently from breastfeeding mothers who have been prescribed this product. The absorption of minoxidil from the scalp is minimal, Hale quotes a level of 1.4% systemically absorbed (Hale and Krutsch Medications and Mothers Milk online access January 2026) and passage into breastmilk is likely to be very limited.
However, Trüeb 2022 reported a case of excessive hair growth on the face of a 2-month-old baby (born prematurely) whose mother used topical minoxidil. (Trüeb RM, Caballero-Uribe N. Minoxidil-induced hypertrichosis in a breastfed infant. J Eur Acad Dermatol Venereol. 2022 Mar;36(3): e224-e225.). The hair growth resolved when the drug was discontinued.
In another case a 9-month-old girl was exposed to 5% topical minoxidil applied to her grandfather’s scalp and developed excessive hair on her body generally. Her grandfather regularly carried her on his back thereby exposing her inadvertently. Exposure was eliminated from the child’s environment and 4 months later her hair distribution returned to normal. (Farsani TT, Kane MJ, Kane KS. Piggyback-acquired hypertrichosis. Pediatr Dermatol. 2014 Jul-Aug;31(4):520-2. doi: 10.1111/pde.12329. Epub 2014 Jun 11. PMID: 24915767).
In December 2005, Suresh et al published the results of a retrospective, post-market observational study. They reported that “Among 2,664 global cases of minoxidil-suspected infantile hypertrichosis, 45 involved children aged 0–23 months: 22.2% due to maternal exposure, 44.4% accidental, and 33.3% unknown” Suresh, J., Saxena, R. & Vivekanandan, K. Understanding the safety profile of topical minoxidil: a retrospective review. Arch Dermatol Res 318, 21 (2026). https://doi.org/10.1007/s00403-025-04469-4. https://link.springer.com/article/10.1007/s00403-025-04469-4#Abs1. They also reported a number of severe eye conditions produced.
If topical minoxidil is used accidental exposure of babies should be avoided by contact with hair, regardless of infant feeding status.
