U.S. flag

An official website of the United States government

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

Cover of Drugs and Lactation Database (LactMed)

Drugs and Lactation Database (LactMed) [Internet].

Show details


Last Revision: September 21, 2020.

Estimated reading time: 3 minutes

CASRN: 74-55-5

image 134970562 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Limited information indicates that maternal doses of ethambutol up to 15 mg/kg daily produce low levels in milk and would not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months. The amount of ethambutol in milk is insufficient to treat tuberculosis in the breastfed infant. The Centers for Disease Control and Prevention and other professional organizations state that breastfeeding should not be discouraged in women taking ethambutol.[1-3]

Drug Levels

Maternal Levels. Information available on ethambutol excretion into breastmilk is limited to 2 cases which were originally reported only as personal communications. One mother had milk levels measured twice while taking ethambutol 15 mg/kg daily. Milk levels were 1.5 mg/L 3 hours after the dose and 1.4 mg/L during a 2-hour period after the dose, but collection methods were not stated. Another woman reportedly had a milk level of 4.6 mg/L which was similar to her plasma level, but her dosage and the milk collection time were not stated. Using these data, reviewers estimated that a breastfed infant would receive 0.51 to 0.86 mg/kg daily which is 3.4 to 5.7% of an infant's therapeutic dose.[4] Using the above sparse data, some authors have estimated that a fully breastfed infant would receive a maximum dose of 0.69 mg/kg daily,[5] which is 4.6% of the maternal weight-adjusted dosage.

A physiologically based pharmacokinetic model of ethambutol predicted that a fully breastfed infant would receive a dose of 0.08 mg/kg daily with a maternal dosage of 24.5 mg/kg daily, which is 0.3% of the weight-adjusted maternal dosage.[6]

Infant Levels. Measured infant serum levels have not been reported. A physiologically based pharmacokinetic model of ethambutol predicted that a fully breastfed infant would achieve a maximum serum concentration of 0.098 mg/L with a maternal dose of 24.5 mg/kg daily.[6]

Effects in Breastfed Infants

In one uncontrolled study, 6-beta-hydroxycortisol levels were measured in 10 male infants whose mothers had tuberculosis and took ethambutol 1 gram daily plus isoniazid 300 mg daily and the infants of mothers (apparently without tuberculosis) who took no chronic drug therapy. The infants of mothers taking the antituberculars had consistently lower 6-beta-hydroxycortisol levels on 8 occasions at 15-day intervals from 90 to 195 days of age, but these differences were statistically significant on days 120 and 195 only. The authors attributed the lower levels to inhibition of hepatic metabolism of cortisol to 6-beta-hydroxycortisol by the antitubercular drugs in milk.[7] However, ethambutol is not known to inhibit drug metabolism, so if the effect occurs it is more likely caused by isoniazid.

Ethambutol was used as part of a seven-drug regimen to treat a pregnant woman with multidrug-resistant tuberculosis during the second and third trimesters of pregnancy and postpartum. The infant was breastfed (extent and duration not stated). At age 4.6 years, the child was developing normally except for a mild speech delay.[8]

Two mothers in Turkey were diagnosed with tuberculosis at the 30th and 34th weeks of pregnancy. They immediately started isoniazid 300 mg, rifampin 600 mg, pyridoxine 50 mg daily for 6 months, plus pyrazinamide 25 mg/kg and ethambutol 25 mg/kg daily for 2 months. Both mothers breastfed their infants (extent not stated). Their infants were given isoniazid 5 mg/kg daily for 3 months prophylactically. Tuberculin skin tests were negative after 3 months and neither infant had tuberculosis at 1 year of age. No adverse effects of the drugs were mentioned.[9]

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date.


Blumberg HM, Burman WJ, Chaisson RE, et al. American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America: treatment of tuberculosis. Am J Respir Crit Care Med. 2003;167:603–62. [PubMed: 12588714]
Anon. Treatment of tuberculosis. MMWR Recomm Rep. 2003;52:1–77. [PubMed: 12836625]
Bartlett JG. Guidelines section. Infect Dis Clin Pract. 2002;11:467–71. [CrossRef]
Snider DE Jr, Powell KE. Should women taking antituberculosis drugs breast-feed? Arch Intern Med. 1984;144:589–90. [PubMed: 6367682]
Fulton B, Moore LL. Antiinfectives in breastmilk. Part III: Antituberculars, quinolones and urinary germicides. J Hum Lact. 1993;9:43–6. [PubMed: 8489724]
Partosch F, Mielke H, Stahlmann R, et al. Exposure of nursed infants to maternal treatment with ethambutol and rifampicin. Basic Clin Pharmacol Toxicol. 2018;123:213–20. [PubMed: 29505119]
Toddywalla VS, Patel SB, Betrabet SS, et al. Can chronic maternal drug therapy alter the nursing infant's hepatic drug metabolizing enzyme pattern? J Clin Pharmacol. 1995;35:1025–9. [PubMed: 8568011]
Drobac PC, del Castillo H, Sweetland A, et al. Treatment of multidrug-resistant tuberculosis during pregnancy: long-term follow-up of 6 children with intrauterine exposure to second-line agents. Clin Infect Dis. 2005;40:1689–92. [PubMed: 15889370]
Keskin N, Yilmaz S. Pregnancy and tuberculosis: To assess tuberculosis cases in pregnancy in a developing region retrospectively and two case reports. Arch Gynecol Obstet. 2008;278:451–5. [PubMed: 18273625]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anti-infective Agents

Antitubercular Agents

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.


Related information

Similar articles in PubMed

  • Review Pyrazinamide[Drugs and Lactation Database (...]
    Review Pyrazinamide
    . Drugs and Lactation Database (LactMed). 2006
  • Review Methylergonovine[Drugs and Lactation Database (...]
    Review Methylergonovine
    . Drugs and Lactation Database (LactMed). 2006
  • Review Trientine[Drugs and Lactation Database (...]
    Review Trientine
    . Drugs and Lactation Database (LactMed). 2006
  • Review Verapamil[Drugs and Lactation Database (...]
    Review Verapamil
    . Drugs and Lactation Database (LactMed). 2006
  • Review Benzathine Penicillin G[Drugs and Lactation Database (...]
    Review Benzathine Penicillin G
    . Drugs and Lactation Database (LactMed). 2006
See reviews...See all...

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...