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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: August 16, 2021.

Estimated reading time: 2 minutes

CASRN: 555-30-6

image 134976346 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Because of the low levels of methyldopa in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. No special precautions are required.

Drug Levels

Maternal Levels. Three women who were 2 to 15 days postpartum were taking 250 mg of methyldopa orally 3 or 4 times daily. Randomly drawn milk samples had levels of drug and conjugate that ranged from < 0.1 to 0.5 mg/L at a dose of 750 mg daily and were 0.8 mg/L at a dose of 1 gram daily.[1]

In 3 women who were 1 to 8 weeks postpartum, peak levels of drug and conjugate occurred between 3 and 6 hours after the dose. Peak levels of drug and conjugate after a dose of 500 mg were 0.2, 0.66 and 1.14 mg/L in 3 mothers' milk. The authors estimated an infant dosage of less than 0.2% of the mother's total dosage.[2]

Infant Levels. No methyldopa was detectable (<200 mcg/L) in the serum of an infant whose mother was taking methyldopa 250 mg twice daily. The infant's urine contained a methyldopa concentration of 3.8 mg/L.[3]

In an 8-week-old infant whose mother was receiving 1 gram daily of methyldopa, a serum level of 90 mcg/L was found 10 hours after a 500 mg maternal dose. Another 1-week-old infant whose mother was receiving 500 mg daily had no detectable drug in the serum (<50 mcg/L).[2]

Effects in Breastfed Infants

No acute or long-term adverse effects were reported in any 15 infants ranging in age from less than 1 week to 8 weeks of age whose mothers were taking oral methyldopa 0.25 to 1.5 grams daily.[1-4]

Effects on Lactation and Breastmilk

Methyldopa can increase serum prolactin and has caused galactorrhea.[5-8] The maternal prolactin level in a mother with established lactation may not affect her ability to breastfeed.

Alternate Drugs to Consider

Enalapril, Hydrochlorothiazide, Methyldopa, Propranolol


Jones HM, Cummings AJ. A study of the transfer of alpha-methyldopa to the human foetus and newborn infant. Br J Clin Pharmacol 1978;6:432-4. Letter. PMID: 728288. [PMC free article: PMC1429559] [PubMed: 728288]
White WB, Andreoli JW, Cohn RD. Alpha-methyldopa disposition in mothers with hypertension and in their breast-fed infants. Clin Pharmacol Ther. 1985;37:387–90. [PubMed: 3838502]
Hauser GJ, Almog S, Tirosh M, et al. Effect of alpha-methyldopa excreted in human milk on the breast-fed infant. Helv Paediatr Acta. 1985;40:83–6. [PubMed: 3843238]
Hoskins JA, Holliday SB. Determination of alpha-methyldopa and methyldopate in human breast milk and plasma by ion-exchange chromatography using electrochemical detection. J Chromatogr. 1982;230:162–7. [PubMed: 7202013]
Arze RS, Ramos JM, Rashid HU, et al. Amenorrhoea, galactorrhoea, and hyperprolactinaemia induced by methyldopa. Br Med J. 1981;283:194. [PMC free article: PMC1506699] [PubMed: 6789964]
Turkington RW. Prolactin secretion in patients treated with various drugs: Phenothiazines, tricyclic antidepressants, reserpine, and methyldopa. Arch Intern Med. 1972;130:349–54. [PubMed: 4560178]
Vaidya RA, Vaidya AB, Van Woert MH, et al. Galactorrhea and Parkinson-like syndrome: An adverse effect of alpha-methyldopa. Metabolism. 1970;19:1068–70. [PubMed: 4923681]
Cohen MA, Davies PH. Drug therapy and hyperprolactinaemia. Adv Drug React Bull 1998:723-6.

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Antihypertensive Agents

Adrenergic alpha-2 Receptor Agonists

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.

Copyright Notice

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

Bookshelf ID: NBK501026PMID: 30000085


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