The Basics
What is Metolazone?
Used to reduce the swelling and fluid retention caused by heart failure or kidney disease; also used alone or with other medications to treat high blood pressure.
Brand names for Metolazone
Metolazone
How Metolazone is classified
Antihypertensive Agents, Thiazide Diuretics
Metolazone During Pregnancy
Metolazone pregnancy category
Category BNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Metolazone while pregnant
Reproduction studies performed in mice, rabbits, and rats treated during the appropriate period of gestation at doses up to 50 mg/kg/day have revealed no evidence of harm to the fetus due to metolazone. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, metolazone tablets should be used during pregnancy only if clearly needed. Metolazone crosses the placental barrier and appears in cord blood.
Taking Metolazone While Breastfeeding
What are recommendations for lactation if you're taking Metolazone?
No information is available on the amount of metolazone in breastmilk. Intense diuresis with large doses may decrease breastmilk production. Other diuretics in low doses are preferred over metolazone.
Maternal / infant drug levels
No information is available on the amount of metolazone in breastmilk. Intense diuresis with large doses may decrease breastmilk production. Other diuretics in low doses are preferred over metolazone.
Possible effects of Metolazone on milk supply
Relevant published information on metolazone 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.[1][2][3] 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.
Possible alternatives to Metolazone
Chlorothiazide, Hydrochlorothiazide.
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. Healy M. Suppressing lactation with oral diuretics. Lancet. 1961;277:1353-4.
2. Reiher KH. [Suppression of lactation by stimulation of diuresis]. Zentralbl Gynakol. 1963;85:188-90. PMID: 13973786
3. Stout G. Suppression of lactation. Br Med J. 1962;1:1150. Letter. PMC: PMC1958377
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
