Sulfamethoxazole use while Breastfeeding
Drugs containing Sulfamethoxazole: Bactrim, Bactrim DS, Septra, SMZ-TMP DS, Co-trimoxazole, Septra DS, Sulfatrim, Bactrim Pediatric, Cotrim, Bactrim IV, Show all 20 »Bethaprim, Gantanol, Bethaprim Pediatric, Sulfatrim Pediatric, Cotrim DS, Cotrim Pediatric, Septra IV, Uroplus, Azo Gantanol, Uroplus DS
Sulfamethoxazole Levels and Effects while Breastfeeding
Summary of Use during Lactation
With healthy, full-term infants it appears acceptable to use sulfamethoxazole during breastfeeding after the newborn period. Until further data are accumulated, alternate agents should probably be used in jaundiced, ill, stressed or premature infants, because of the risk of bilirubin displacement and kernicterus. Sulfamethoxazole should be avoided while breastfeeding a G6PD-deficient infant.
Maternal Levels. Forty women who were 5 or fewer days postpartum period received oral co-trimoxazole equivalent to 800 mg of sulfamethoxazole twice daily. Another 10 women were given this dose three times daily. Milk levels were measured several times daily for 5 days. Average sulfamethoxazole levels were 4.5 and 5.3 mg/L, respectively, with the 2 dosages. With the usual dose of sulfamethoxazole 800 mg daily, an exclusively breastfed infant would be expected to receive 0.68 mg/kg daily of sulfamethoxazole. This is very low in comparison to the established treatment dosage 40 mg/kg daily for infants over 2 months of age.
Infant Levels. Relevant published information was not found as of the revision date.
Effects in Breastfed Infants
An extensive systematic review of the use of sulfonamides near term and during breastfeeding found no adverse reactions in infants. The authors concluded that use of sulfamethoxazole during breastfeeding presents no risk of neonatal kernicterus.
A prospective, controlled study asked mothers who called an information service about adverse reactions experience by their breastfed infants. Of 12 women who took sulfamethoxazole and trimethoprim during breastfeeding (time postpartum and dosage not reported), none reported diarrhea, drowsiness or irritability in her infant. Two mothers reported poor feeding in their infants.
Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.
Alternate Drugs to Consider
1. Chung AM, Reed MD, Blumer JL. Antibiotics and breast-feeding: a critical review of the literature. Paediatr Drugs. 2002;4:817-37. PMID: 12431134
2. Miller RD, Salter AJ. The passage of trimethoprim/sulfamethoxazole into breast milk and its significance. In: Daikos CK, ed. Progress in Chemotherapy. Antibacterial chemotherapy. 1974;1:687-91.
3. Forna F, McConnell M, Kitabire FN et al. Systematic review of the safety of trimethoprim-sulfamethoxazole for prophylaxis in HIV-infected pregnant women: implications for resource-limited settings. AIDS Rev. 2006;8:24-36. PMID: 16736949
4. Ito S, Blajchman A, Stephenson M et al. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168:1393-9. PMID: 8498418
CAS Registry Number
LactMed Record Number
Last Revision Date
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.