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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

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Drugs and Lactation Database (LactMed®) [Internet].

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Last Revision: January 18, 2021.

Estimated reading time: 1 minute

CASRN: 10118-90-8

image 134989698 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Many reviews state that tetracyclines are contraindicated during breastfeeding because of possible staining of infants' dental enamel or bone deposition of tetracyclines. However, a close examination of available literature indicates that there is not likely to be harm in short-term use of minocycline during lactation because milk levels are low and absorption by the infant is inhibited by the calcium in breastmilk. Short-term use of minocycline is acceptable in nursing mothers. As a theoretical precaution, avoid prolonged or repeat courses during nursing. Monitor the infant for rash and for possible effects on the gastrointestinal flora, such as diarrhea or candidiasis (thrush, diaper rash). Black discoloration of breastmilk has been reported with minocycline. Topical minocycline for acne by the mother poses no risk to the breastfed infant.

Drug Levels

Maternal Levels. After a single dose of minocycline 200 mg orally in 2 patients (time postpartum not stated), a peak milk level of 0.8 mg/L occurred at 6 hours after the dose. Average milk levels ranged between 0.5 and 0.8 mg/L during the 12 hours after the dose and a total of 18 mcg was excreted during this time.[1]

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

Effects in Breastfed Infants

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

Effects on Lactation and Breastmilk

A woman taking minocycline 100 mg twice daily for almost 4 years developed galactorrhea after taking perphenazine, amitriptyline and diphenhydramine, and the breast secretion was black in color.[2]

Another woman who had nursed her infant and produced occasional small amounts of breastmilk during the 18 months after weaning was given oral minocycline 150 mg daily. After 3 to 4 weeks, expressed milk had become black. Iron levels in milk were over 100 times greater than that found in normal milk. A mammogram was normal.[3]

In both of these cases, macrophages containing a black, iron-containing pigment were found in milk. It is thought that the pigment is an iron chelate of minocycline or one of its metabolites.[2,3]

Alternate Drugs to Consider

Doxycycline, Tetracycline


Mizuno S, Taketa M, Sano S, et al. Minocycline. Jpn J Antibiot. 1969;22:473–9. [PubMed: 4909972]
Basler RS, Lynch PJ. Black galactorrhea as a consequence of minocycline and phenothiazine therapy. Arch Dermatol. 1985;121:417–8. [PubMed: 4038862]
Hunt MJ, Salisbury EL, Grace J, et al. Black breast milk due to minocycline therapy. Br J Dermatol. 1996;134:943–44. [PubMed: 8736342]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anti-Infective Agents

Antibacterial 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.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK501031PMID: 30000090


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