Can I take sulfasalazine while pregnant or breastfeeding?

Pregnancy: There are no adequate and well-controlled studies of sulfasalazine in pregnant women. Reproduction studies have been performed in rats and rabbits at doses up to 6 times the human maintenance dose of 2 g/day based on body surface area and have revealed no evidence of impaired female fertility or harm to the fetus due to sulfasalazine. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. There have been case reports of neural tube defects (NTDs) in infants born to mothers who were exposed to sulfasalazine during pregnancy, but the role of sulfasalazine in these defects has not been established. However, oral sulfasalazine inhibits the absorption and metabolism of folic acid which may interfere with folic acid supplementation (see Drug Interactions ) and diminish the effect of periconceptional folic acid supplementation that has been shown to decrease the risk of NTDs. A national survey evaluated the outcome of pregnancies associated with inflammatory bowel disease (IBD).

Prescribing label, section “Pregnancy” (opening excerpt): Sulfasalazine (oral), Mylan Pharmaceuticals Inc. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.

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. Numerous experts and professional guidelines have stated that the drug is a low risk to the nursing infant and acceptable to use during breastfeeding.[2-8] 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.

“Summary of Use during Lactation”, LactMed record “Sulfasalazine” (LM442), quoted verbatim. Everything LactMed reports about Sulfasalazine while breastfeeding.

Nursing Mothers: Sulfonamides, including sulfasalazine, are present in human milk (see Pregnancy, Clinical Considerations ). Insignificant amounts of sulfasalazine have been found in milk, whereas levels of the active metabolite sulfapyridine in milk are about 30 to 60 percent of those in the maternal serum. Caution should be exercised when sulfasalazine delayed release tablets are administered to a nursing mother. There are reports with limited data of bloody stools or diarrhea in human milk fed infants of mothers taking sulfasalazine. In cases where the outcome was reported, bloody stools or diarrhea resolved in the infant after discontinuation of sulfasalazine in the mother or discontinuation of breastfeeding. Due to limited data, a causal relationship between sulfasalazine exposure and bloody stools or diarrhea cannot be confirmed or denied. Monitor human milk fed infants of mothers taking sulfasalazine for signs and symptoms of diarrhea and/or bloody stools.

Prescribing label, section “Nursing Mothers”: Sulfasalazine (oral), Mylan Pharmaceuticals Inc. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.