Methenamine use while Breastfeeding
Drugs containing Methenamine: Uribel, Hiprex, Cystex, Urelle, Urex, Hyophen, Uta, Urised, Uretron, Phosphasal, Show all 47 »Uretron DS, Ustell, Urogesic Blue, Methylphen, Mandelamine, Urimax, Darpaz, Prosed DS, Utira, Uro Blue, Urin D/S, Uritact DS, UTICAP, Utrona, UR N-C, Utrona-C, Phosenamine, Utira-C, Darcalma, Visqid AA, Utac, Uroqid-Acid No2, Uro-Phosphate, Atrosept, Dolsed, Cystemms-V, Uritin, Trac Tabs 2x, Urisedamine, Urapine, MSP-Blu, UriSym, Uritact-EC, Prosed EC, Usept, MHP-A, 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
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