Is Sulfasalazine safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Sulfasalazine. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
One group of investigators stated that they had 10 years of experience using sulfasalazine during the puerperium with no obvious adverse effects in breastfed infants.[ 9 ] The breastfed infant of a mother taking sulfasalazine 500 mg 4 times daily beginning at 4.5 months postpartum experienced no adverse effects during 2.5 months of nursing.[ 11 ] A 2-month-old breastfed infant whose mother was taking sulfasalazine 3 grams daily had an episode of bloody diarrhea. The bloody diarrhea recurred 2 weeks later and persisted until 3 months of age. The infant had up to 6 bowel movements daily and the stools had a loose consistency and were mixed with fresh blood. A colonoscopy revealed a mild inflammatory process and numerous punctate erosions in the mucosa. The infant had a sulfapyridine blood level of 5.3 mg/L, which may have been enhanced because the infant's mother was a slow acetylator. The bloody diarrhea stopped 48 to 72 hours after the mother stopped taking sulfasalazine. A repeat colonoscopy at 4.5 months of age was normal and no further bloody diarrhea occurred up to 14 months of follow-up. The authors felt that the reaction was likely caused by an allergic reaction to sulfapyridine.[ 14 ] The reaction was probably caused by sulfasalazine or one of its metabolites in breastmilk. Both sulfapyridine and mesalamine have been reported to cause diarrhea in breastfed infants.[ 15 , 16 ] Eight infants whose mothers were taking sulfasalazine in average dosage of 2.6 grams daily were breastfed. Sulfapyridine was detectable in 5 infant's serum in levels ranging from 1 to 4.8 mg/L. The authors pointed out that these levels were far below those required to displace bilirubin from serum albumin binding sites.[ 13 ] A case-control study compared the infants of mothers taking mesalamine (n = 117; average dose, 2065 mg daily), olsalazine (n = 2) or sulfasalazine (n = 2) to infants of matched control mothers (n = 121) who were exposed to no treatment known to be harmful to a breas
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Sulfasalazine is a chemical combination of sulfapyridine and mesalamine (5-aminosalicylic acid; 5-ASA) which is considered to be the active component. Sulfapyridine is metabolized to acetylated and glucuronide metabolites. Mesalamine is metabolized to N-acetyl-5-ASA, which is inactive in treating inflammatory bowel disease, but its effects on the breastfed infant are unknown. Maternal Levels. Three women who were taking 500 mg of sulfasalazine 4 times daily had breastmilk samples analyzed 1 week postpartum. The times of the samples in relation to the doses were not stated. Sulfasalazine milk levels averaged 2.7 mg/L, total sulfapyridine (including all metabolites) averaged 10.3 mg/L and free sulfapyridine (not including metabolites) was 6.5 mg/L. Mesalamine and its metabolites were not measured.[ 9 ] Twelve patients with inflammatory bowel disease started sulfasalazine 3 weeks postpartum and had breastmilk levels taken 2 to 3 weeks later. Of 31 samples in the 12 women, only 5 samples had detectable ( 1 mg/L) sulfasalazine levels, ranging from 1.5 to 2.5 mg/L with dosages of 1 or 2 grams of sulfasalazine daily. Eight of the patients had 16 untimed milk levels measured while taking dosages of 1 to 3 grams daily. Milk sulfapyridine levels ranged from 1 to 38 mg/L, with some correlation to dosage. Almost no sulfapyridine metabolites were found in milk.[ 10 ] A woman began taking sulfasalazine 500 mg 4 times daily at 4.5 months postpartum for ulcerative colitis. She provided milk samples on 8 days over the next 2 months. A total of 44 samples were obtained, including 10 on the first day of medication. Other samples were obtained midway between nursing bouts which occurred about every 4 hours. Sulfasalazine was not found in any of the milk samples. Sulfapyridine appeared in milk 4 hours after the first dose in a concentration of 4.8 mg/L. Over the next 2 weeks, sulfapyridine levels fluctuated in the range of 3.9 to 6.6 mg/L and acetylsulfapyridine levels were in the range
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.