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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Last Revision: October 31, 2018.

Estimated reading time: 1 minute

CASRN: 58-94-6

Chemical structure

Drug Levels and Effects

Summary of Use during Lactation

Low-dose chlorothiazide appears to be acceptable during lactation. Intense diuresis with large doses may decrease breastmilk production.

Drug Levels

Maternal Levels. After a single dose of 500 mg of chlorothiazide orally, there was no detectable drug (<1 mg/L) in the breastmilk from 11 nursing mothers at 1, 2 and 3 hours after the dose.[1]

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

Effects in Breastfed Infants

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

Effects on Lactation and Breastmilk

Relevant published information on chlorothiazide was not found as of the revision date. Intense diuresis with thiazides and thiazide-like diuretics, fluid restriction and breast binding have been used to suppress postpartum lactation.[2][3][4] The added contribution of the diuretic to these measures, which are effective in suppressing lactation, has not been studied. There are no data on the effects of diuretics on established, ongoing lactation.

Alternate Drugs to Consider



Werthmann MW Jr, Krees SV. Excretion of chlorothiazide in human breast milk. J Pediatr. 1972;81:781-3. [PubMed: 5074355]
Healy M. Suppressing lactation with oral diuretics. Lancet. 1961;1:1353-4.
Stout G. Suppression of lactation. Br Med J. 1962;1:1150. Letter. PMC: PMC1958377.
Reiher KH. [Suppression of lactation by stimulation of diuresis] Zentralbl Gynakol. 1963;85:188-90. [PubMed: 13973786]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

  • Breast Feeding
  • Antihypertensive Agents
  • Thiazide Diuretics

Disclaimer: 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.


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