Methenamine Hippurate

Drug Levels and Effects:

Summary of Use during Lactation:

Methenaminepasses into milk in small quantities and appears safe to use, even while nursing a newborn.

Drug Levels:

Maternal Levels.

Six mothers nursing newborn infants were givenmethenaminehippurate1 g orally. Five hours after the dose, a meanmethenamineconcentration of 7 mg/L was found in milk. In two other women, milk concentrations averaged 9.1 mg/L 2 to 3 hours after a 1 g dose ofmethenaminehippurateorally and 4.3 mg/L 6 to 7 hours after the dose. Based on the amount of milk ingested, the authors calculated the dose the infants received to be 0.05 to 0.1 mg/kg which is about 1% of the adult dose.[1]

Infant Levels.

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

Effects in Breastfed Infants:

Four newborn infants were allowed to breastfeed in one study after a maternal dose of 1 g ofmethenaminehippurate. No adverse effects were reported.[1]

Possible Effects on Lactation:

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

Alternate Drugs to Consider:



1. Allgen LG, Holmberg G, Persson B, Sorbo B. Biological fate ofmethenaminein man. Acta Obstet Gynecol Scand. 1979;58:287-93. PMID:484222

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Anti-Infective Agents, Urinary

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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