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.

Possible Effects on Lactation:

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:



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

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Antihypertensive Agents

  • Thiazide Diuretics

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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