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.

Possible Effects on Lactation:

Chlorthalidonehas been used successfully to suppress lactation by giving 200 mg orally right after delivery, followed by 100 mg dailyy 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:



1. Mulley BA, Parr GD, Pau WK et al. Placental transfer of chlorthalidone and its elminination in maternal milk. Eur J Clin Pharmacol. 78;13:129-31. PMID:658109
2. Reiher KH. [Suppression of lactation by stimulation of diuresis]. Zentralbl Gynakol. 1963;85:188-90. PMID:13973786
3. Vercruysse J. [Inhibition of lactation. Comparative study of an estro-androgen and of a diuretic]. Brux Med. 1966;46:1258-66. PMID:6011090

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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