Methenamine use while Breastfeeding
Drugs containing Methenamine: Uribel, Hiprex, Cystex, Urelle, Uta, Hyophen, Ustell, Urex, Urimax, Phosphasal, Show all 47 »Urised, Uretron DS, Methylphen, Urogesic Blue, Prosed DS, Uretron, Utac, Uroqid-Acid No2, UTICAP, Darpaz, Utira, Trac Tabs 2x, Urin D/S, MSP-Blu, Uro Blue, Usept, Uritact DS, Phosenamine, Utira-C, Utrona-C, Darcalma, Visqid AA, Mandelamine, Uro-Phosphate, Uritin, Cystemms-V, Urapine, Dolsed, Atrosept, Urisedamine, MHP-A, Prosed EC, UR N-C, Uritact-EC, Utrona, UriSym, Urimar-T
Methenamine Levels and Effects while Breastfeeding
Summary of Use during Lactation
Both the hippurate and mandelate salts of methenamine pass into milk in small quantities and appear acceptable to use, even while nursing a newborn.
Maternal Levels. Six mothers nursing newborn infants were given methenamine hippurate 1 g orally. Five hours after the dose, a mean methenamine concentration 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 of methenamine hippurate orally 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.
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 gram of methenamine hippurate. No adverse effects were reported.
Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.
Alternate Drugs to Consider
1. Allgen LG, Holmberg G, Persson B et al. Biological fate of methenamine in man. Acta Obstet Gynecol Scand. 1979;58:287-93. PMID: 484222
CAS Registry Number
Antiinfective Agents, Urinary
LactMed Record Number
Last Revision Date
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.