Is Zafirlukast safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Zafirlukast. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Relevant published information was not found as of the revision date. The manufacturer reports that after administration of zafirlukast 40 mg twice daily to lactating women (number not reported), average steady-state milk concentrations were 50 mcg/L. Using these data, a fully breastfed infant would be expected to receive about 0.6% of the maternal weight-adjusted dosage. Infant Levels. Relevant published information was not found as of the revision date.
Alternatives LactMed lists
“No published information” means the studies do not exist yet — not that Zafirlukast is known to be harmful, and not that it is known to be safe. Your prescriber or pharmacist can weigh your baby's age and whether a better-studied alternative would do the same job. Worth asking before stopping a medicine you need.
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.