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Can you take olsalazine while breastfeeding?

By the pharmaranks editorial teamReviewed against the NIH/NLM Drugs and Lactation Database (LactMed) sourcesUpdated Dec 15, 2025How we research

What LactMed says

The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.

Limited data indicate that olsalazine is poorly excreted into breastmilk. However, olsalazine is a mesalamine prodrug. Rather high levels of the mesalamine metabolite N-acetyl-5-ASA appear in breastmilk and its effects on breastfed infants are unknown. A few cases of diarrhea have been reported in infants exposed to mesalamine, although the rate is not high. Most experts consider mesalamine derivatives to be acceptable during breastfeeding. If olsalazine is required by the mother, it is not a reason to discontinue breastfeeding, but carefully observe breastfed infants for diarrhea during maternal use of olsalazine.

Quoted from Olsalazine — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised December 15, 2025.

What LactMed would consider instead

LactMed ends this record by naming the drugs it would consider in place of olsalazine. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.

How much olsalazine gets into breastmilk

Olsalazine is a prodrug that liberates the active drug, mesalamine (5-aminosalicylic acid; 5-ASA), in the gastrointestinal tract. Mesalamine is metabolized to N-acetyl-5-ASA, which is inactive in treating inflammatory bowel disease, but its possible effects on the breastfed infant are unknown.

Maternal Levels. A lactating woman with a long history of Crohn's disease and 2 bowel resections at her terminal ileum was given a single oral dose of olsalazine 500 mg at 4 months postpartum. She was also taking prednisone 17.5 mg daily at the time of the study. Milk samples were taken periodically from 30 minutes to 48 hours after the dose. Olsalazine and its metabolites, olsalazine sulfate and mesalamine were undetectable (<170 mcg/L) in milk at all times during the study. The inactive mesalamine metabolite, N-acetyl-5-ASA, was detectable only at 10, 14 and 24 hours after the dose in concentrations of 170, 183 and 264 mcg/L, respectively.

A woman taking olsalazine capsules 750 mg twice daily collected 5 breastmilk samples over one day at 2 to 4 weeks postpartum. Mesalamine was undetectable (<20 mcg/L) in milk. N-acetyl-5-ASA averaged 2.3 mg/L (range 1.2 to 3.8 mg/L) in the 5 samples. The highest milk level was in the 6 pm sample, but the times of the doses were not stated.

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

What has been seen in breastfed infants

One infant was breastfed during maternal therapy with olsalazine for Crohn's disease. After 2 and 3 weeks of therapy, no rash, wheezing, vomiting or diarrhea were noted in the infant.

The active metabolite of olsalazine, mesalamine, was probably responsible for diarrhea in a 6-week-old whose diarrhea recurred 4 times after rechallenging the mother 4 times during breastfeeding.

In a prospective telephone follow-up study, 8 nursing mothers reported taking mesalamine (dosage and route unspecified). One mother reported diarrhea in her infant. No other adverse reactions were reported in the infants by their mothers.

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 breastfed infant. Infants were exposed to mesalamine through milk for a mean of 5.3 months (range: 3 days-24 months). Infants were breastfed for an average of about 7.4 months and were followed up at an average age of about 22 months. No difference in the frequency or characteristics of maternally reported adverse events were found between exposed and control infants.

Effects on milk supply

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

Frequently asked questions

Can you take olsalazine while breastfeeding?

Limited data indicate that olsalazine is poorly excreted into breastmilk. The full record is quoted on this page, and the decision is one to make with the person who prescribed it — LactMed itself states it is not a substitute for professional judgement.

What can I take instead of olsalazine while breastfeeding?

LactMed lists Adalimumab, Azathioprine, Budesonide, Certolizumab Pegol, Infliximab, Mesalamine, Prednisone, Sulfasalazine as alternate drugs to consider. That is the database's own list for this drug — whether any of them suits you depends on what you are treating.

Does olsalazine pass into breastmilk?

LactMed's measured drug levels for olsalazine are quoted in full on this page, under "How much gets into breastmilk".

Do I need to pump and dump after taking olsalazine?

LactMed does not frame its records that way — it reports measured drug levels in milk and what has been observed in breastfed infants, which is what this page quotes. "Pump and dump" advice for a specific drug and dose should come from your clinician or a pharmacist, not from a general rule.

More on olsalazine

LactMed states that the information it presents is not a substitute for professional judgement, and that you should consult your healthcare provider for breastfeeding advice related to your particular situation. Nothing on this page is medical advice.