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Methenamine use while Breastfeeding

Medically reviewed by Last updated on Dec 5, 2023.

Drugs containing Methenamine: Hiprex, Uribel, Cystex Urinary Pain Relief, Uro-MP, Urogesic Blue, Urimax, Cystex, Uretron DS, Hyophen, Vilamit MB, Show all 59 »Phosphasal, Urimar-T, Ustell, Uta, Uribel Tabs, Usept, Uro-L, Uralgic, Urelle, Urex, Urised, Prosed DS, Methylphen, Urophen MB, Urisedamine, Dolsed, Cystemms-V, Urapine, MSP-Blu, MHP-A, Uritact DS, UriSym, Uritact-EC, Utrona-C, Darpaz, UTICAP, Phosenamine, Darcalma, Urin D/S, Utira-C, Azuphen MB, UroAv-B, UroAv-81, Hyolev MB, Uramit MB, UR N-C, UrNeva, Vilevev MB, Uro-SP, Uro-458, Uro Blue, Indiomin MB, Urolet MB, Mandelamine, Uroqid-Acid No2, Utac, Visqid AA, Uro-Phosphate, Uro-Pain Dual Action

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 gram 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 at 2 to 3 hours after a 1 gram dose of methenamine hippurate orally and 4.3 mg/L at 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


Allgén LG, Holmberg G, Persson B, et al. Biological fate of methenamine in man. Acta Obstet Gynecol Scand. 1979;58:287–93. [PubMed: 484222]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anti-Infective Agents, Urinary

Antibacterial Agents

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Further information

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