In: Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006.


Sulfasalazine and its active metabolite mesalamine are poorly excreted into breastmilk. However, rather high levels of the mesalamine metabolite N-acetyl-5-ASA appear in breastmilk and its effects on breastfed infants are unknown. Another sulfasalazine metabolite, sulfapyridine, also appears in milk and infant serum and might cause hemolysis, especially in newborn infants and in those with glucose-6-phosphate dehydrogenase (G6PD) deficiency. The time of greatest risk for hemolysis in fullterm newborns without G6PD deficiency might be as short as 8 days after birth.[1] Bloody diarrhea has occurred in an infant whose mother was taking sulfasalazine and a few cases of diarrhea have been reported in infants exposed to mesalamine in breastmilk, although the rate is not high. Most experts and professional guidelines consider mesalamine derivatives to be safe during breastfeeding.[2-9] If the mother requires sulfasalazine, it is not a reason to discontinue breastfeeding, but carefully observe breastfed infants for diarrhea. Other mesalamine derivatives that do not contain a sulfonamide are preferred.

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