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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

Cover of Drugs and Lactation Database (LactMed)

Drugs and Lactation Database (LactMed) [Internet].

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Last Revision: October 31, 2018.

Estimated reading time: 1 minute

CASRN: 38304-91-5

Chemical structure

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. Topical minoxidil should pose low risk to the breastfed 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 for 2 months of maternal minoxidil therapy.[1]

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. [PubMed: 3966734]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

  • Breast Feeding
  • Antihypertensive Agents
  • Vasodilator Agents

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.


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