Minoxidil Use and Breastfeeding: Is it always risk free?

New Study Suggests that Prematurity and Ethnic Background Could be Risk Factors.

It is well know that minoxidil should not be used by pregnant mothers. Mothers who use topical minoxidil during pregnancy are at risk to have babies that have heart, brain and vascular problems as well as the infants showing excessive hair growth or hypertrichosis.

Less is known about the safety of minoxidil by mothers who are breastfeeding. The American Academy of Pediatrics and the American Academy of Dermatology generally view topical minoxidil use by breastfeeding mothers as quite safe.

Valdivieso et al 1985

A 1985 case report reminds us of the seemingly good safety of minoxidil for infants who are breastfeeding. The authors described in their report a 2- month-postpartum mother taking fairly high doses of ORAL minonxidil (5 mg twice daily up to 7.5 mg at once). The baby did not experience any type of hypertrichosis or other abnormal signs for 2 months of maternal minoxidil therapy.

Trueb et al, 2022

Trueb et al recently reported a female infant who developed facial hypertrichosis from her mother using 5% topical minoxidil twice daily. Hair growth was noted at age 2 months.

The baby girl was born 4 weeks prematurely with a birth weight of 2190 g and body length of 46 cm. The baby girl was of Syrian origin with black hair. Fortunately, the hypertrichosis was completely reversible after cessation of maternal minoxidil treatment.

Conclusions

This is a helpful report. It reminds us that hypertrichosis from minoxidil is possible in infants if mothers use topical minoxidil. Fortunately it’s not common and the authors in this report here propose that risk factors might include a) prematurity and low weight and b) ethnic background.

More studies are clearly needed regarding the precise risk factors that increase the risk of hypertrichosis in breast feeding mothers.

I personally always recommend that mothers start minoxidil after the baby’s first month of life and don’t recommend that mothers start up in the first 4 weeks. One thing that has always struck me in Pediatrics is that there something very delicate and precious about the first 4 weeks of human life and so this is why I have adopted this policy for many years in my practice. Perhaps this study would remind me that it should probably be the first month of ‘corrected’ age. So if a baby is born premature by 1 month, it might make sense for the mom to start topical minoxidil at month 2. This is all guess work and all theoretical. Nevertheless, this was a helpful study.

I wonder if the little girl also had hair on the back. In my experience the forehead and midline back are very sensitive to minoxidil induced hypertrichosis in infants and babies who have been exposed. This report did not mention it but it would be interested to note. I often remind new mothers who use minoxidil just to keep a watch on the forehead and back to see if there is any evidence of hypertrichosis. Fortunately it’s quite uncommon for there to be any such growth.

REFERENCE

Trueb RM et al. Minoxidil-induced hypertrichosis in a breastfed infant. J Eur Acad Dermatol Venereol . 2022 Mar;36(3):e224-e225.n

Claudet I, Cortey C, Honorat R, Franchitto N. Minoxidil topical solution: an unsafe product for children. Pediatr Emerg Care 2015; 31: 44–46.

Valdivieso A, Valdes G, Spiro TE et al. Minoxidil in breast milk. Ann Intern Med 1985; 102: 135.