Can you take abatacept while breastfeeding?
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.
Abatacept is a large fusion protein that interferes with T-cell activation. It has a molecular weight of 92,000, so only small amounts are expected to enter breastmilk and absorbed by the infant. Case reports indicate that amounts in milk are very low and do not appear to affect the breastfed infant. Some professional guidelines consider abatacept to be acceptable during breastfeeding. Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.
Quoted from Abatacept — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised May 15, 2025.
What LactMed would consider instead
LactMed ends this record by naming the drugs it would consider in place of abatacept. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.
How much abatacept gets into breastmilk
Maternal Levels. A woman with rheumatoid arthritis resumed weekly doses of abatacept 125 mg subcutaneously 2 days after delivery. Maternal serum and breastmilk samples were obtained after the 9th and 10th doses. Peak abatacept concentrations in milk occurred at about 3 days after each dose at 256 mcg/L. Prior to the next dose, the trough concentration was 170 mcg/L. The authors estimated the daily infant dose to be between 25 and 38 mcg/kg, which translates into a weight-adjusted percent of maternal dosage of 1 to 1.5% (median 1.3%).
Two lactating women who were receiving abatacept for rheumatoid arthritis donated milk samples for analysis. The first, who was receiving a subcutaneous dose of 125 mg once weekly, had a peak milk level of about 200 mcg/L at 3 days after the dose and a level of about 100 mcg/L at 7 days after the dose. The second, who was receiving an intravenous dose of 500 mg every 2 weeks, had a peak milk level of about 100 mcg/L at 3 days after the dose and a level of about 50 mcg/L at 7 days after the dose.
Infant Levels. Relevant published information was not found as of the revision date.
What has been seen in breastfed infants
A woman with rheumatoid arthritis resumed weekly doses of abatacept 125 mg subcutaneously 2 days after delivery. Her infant was exclusively breastfed up until 12 months of age. Her infant had no adverse effects and developed normally during this time. She also received routine childhood vaccinations at 3 months of age as well as rotavirus and BCG vaccination at 6 months of age. No infections or adverse immune reactions were seen following the vaccinations.
Effects on milk supply
Relevant published information was not found as of the revision date.
Frequently asked questions
Can you take abatacept while breastfeeding?
Abatacept is a large fusion protein that interferes with T-cell activation. 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 abatacept while breastfeeding?
LactMed lists Adalimumab, Certolizumab Pegol, Etanercept, Infliximab, Tocilizumab 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 abatacept pass into breastmilk?
LactMed's measured drug levels for abatacept are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking abatacept?
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 abatacept
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.