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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

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Drugs and Lactation Database (LactMed®) [Internet].

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Last Revision: January 18, 2021.

Estimated reading time: 1 minute

CASRN: 77-36-1

image 135269872 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Although amounts of chlorthalidone in milk are not great, its slow clearance may lead to accumulation in the infant, especially while nursing a newborn or preterm infant. It may also suppress lactation. An alternate drug may be preferred.

Drug Levels

Maternal Levels. In 7 women taking 50 mg of oral chlorthalidone daily prior to and after delivery, milk levels 3 days after delivery (collection times unspecified) ranged from 90 to 860 mcg/L. The authors estimated that the infant would receive about 180 mcg daily of chlorthalidone from milk at this maternal dosage.[1] This would amount to about 6% of the maternal weight-adjusted dosage.

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

Chlorthalidone has been used successfully to suppress lactation by giving 200 mg orally right after delivery, followed by 100 mg daily for 3 days in conjunction with fluid restriction and breast binding.[2] However, a comparative study found no difference between chlorthalidone 200 mg daily for 7.6 days and placebo in milk leakage and breast engorgement and pain.[3] The added contribution of the diuretic to fluid restriction and breast binding, 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

Chlorothiazide, Hydrochlorothiazide


Mulley BA, Parr GD, Pau WK, et al. Placental transfer of chlorthalidone and its elimination in maternal milk. Eur J Clin Pharmacol. 1978;13:129–31. [PubMed: 658109]
Reiher KH. Zentralbl Gynakol. 1963;85:188–90. [Suppression of lactation by stimulation of diuresis] [PubMed: 13973786]
Vercruysse J. Brux Med. 1966;46:1258–66. [Inhibition of lactation. Comparative study of an estro-androgen and of a diuretic] [PubMed: 6011090]

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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Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK501562PMID: 30000622


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