Is Methylene Blue safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Methylene Blue. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
An old paper found that breastmilk was not discolored after administration to nursing mothers, possibly indicating the lack of passage into milk. This is consistent with the drug being 94% protein bound. However, current labeling states that breastfeeding should be discontinued during and for up to 8 days after administration, apparently based on its half-life of 24 hours. No information is available on the safety of oral methylene blue during breastfeeding.
Effects on the breastfed infant
In an old study, 150 mg of methylene blue was given (presumably intravenously) to nursing mothers on several occasions. The presence of the blue dye was verified in the urine, which it colored intensely. No bluish tint was observed in the milk, indicating that methylene blue was not excreted unchanged. During the day of ingestion and the following four days, the chromogen was sought in the milk using the usual method (acidification with acetic acid, boiling, centrifugation, and examination of the supernatant liquid). No trace of the chromogen could be detected.[1]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Relevant published information was not found as of the revision date.
Infant Levels. Relevant published information was not found as of the revision date.
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Methylene Blue” (methylene_blue). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.