Publication Details

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CASRN: 38304-91-5

image 135002087 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Because of the minimal amount of information on this potent agent, use minoxidil with caution, particularly when therapy involves a large maternal dosage or breastfeeding a newborn. Maternal topical minoxidil should pose low risk to older, full-term breastfed infants, but might best be avoided while breastfeeding a preterm or neonatal infant.

Drug Levels

Maternal Levels. In one case report, a 2-month-postpartum mother who was taking minoxidil 5 mg twice daily was given a, oral dose of 7.5 mg. The peak milk level of minoxidil plus glucuronide conjugate was 45.1 mcg/L at 1 hour after the dose. Milk levels paralleled serum levels, falling rapidly after the first hour to a concentration of 12.4 mcg/L at 3 hours, 4 mcg/L at 6 hours, 1.9 mcg/L at 9 hours, 0.8 mcg/L at 12 hours after the dose.[1]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

No hypertrichosis or other abnormal signs were seen in one infant breastfed (extent not stated) for 2 months of maternal minoxidil 5 mg twice daily by mouth. The mother was taking the drug throughout pregnancy and postpartum and the infant was born at 37 weeks of gestation.[1]

Another breastfed (extent not stated) infant who was born 4 weeks preterm developed facial hypertrichosis while her mother was using 5% minoxidil topically twice a day. The infant appeared normal at 2 weeks of age, but had considerable black hair on the forehead at 2 months of age. The mother discontinued minoxidil and at 6 months of age, the infant had lost the excess hair. The time course of minoxidil use and hair growth was not clearly specified in the report.[2] The reaction was possibly caused by minoxidil in milk, but no documentation of maternal or infant serum levels or milk levels was made and normal transient neonatal hypertrichosis is the possible cause.

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date.

Alternate Drugs to Consider

Enalapril, Hydrochlorothiazide, Methyldopa, Propranolol


Valdivieso A, Valdes G, Spiro TE, et al. Minoxidil in breast milk. Ann Intern Med 1985;102:135. Letter. PMID: 3966734. [PubMed: 3966734]
Trüeb RM, Caballero-Uribe N. Minoxidil-induced hypertrichosis in a breastfed infant. J Eur Acad Dermatol Venereol. 2022;36:e224–e5. [PubMed: 34657321]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Antihypertensive Agents

Vasodilator Agents

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