Skip to Content

Methenamine use while Breastfeeding

Drugs containing Methenamine: Uribel, Hiprex, Cystex, Phosphasal, Urogesic Blue, Urelle, Urimax, Ustell, Hyophen, Uretron, Show all 60 »Uro-MP, Uretron DS, Mandelamine, Urex, Utira-C, Urin D/S, Uta, Urimar-T, Vilamit MB, Uritin, Urised, Phosenamine, Prosed EC, UriSym, Usept, Hyolev MB, Uramit MB, UR N-C, Vilevev MB, Uro-458, Urophen MB, Indiomin MB, Uro Blue, UroAv-B, Urolet MB, Methylphen, Uroqid-Acid No2, Utac, Visqid AA, UroAv-81, Azuphen MB, Uritact DS, Prosed DS, Utira, Utrona, UTICAP, Uritact-EC, Darcalma, Darpaz, Utrona-C, MHP-A, Uro-L, MSP-Blu, Urisedamine, Urapine, Cystemms-V, Dolsed, Atrosept, Trac Tabs 2x, Uro-Phosphate

Medically reviewed on September 7, 2017

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.

Drug Levels

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.[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 gram of methenamine hippurate. No adverse effects were reported.[1]

Effects on Lactation and Breastmilk

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

Alternate Drugs to Consider

Methenamine Hippurate, Methenamine Mandelate


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

Methenamine Identification

Substance Name


CAS Registry Number


Drug Class

Antiinfective Agents, Urinary

Antibacterial Agents

Administrative Information

LactMed Record Number



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.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.