Can I take ondansetron while pregnant or breastfeeding?

Pregnancy Teratogenic Effects Pregnancy Category B. Reproduction studies have been performed in pregnant rats and rabbits at daily oral doses up to 15 and 30 mg/kg/day, respectively, and have revealed no evidence of impaired fertility or harm to the fetus due to ondansetron. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed

Prescribing label, section “Pregnancy”: ondansetron (oral), Bryant Ranch Prepack. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.

Ondansetron is frequently used for nausea during and after cesarean section, usually in doses of 4 to 8 mg intravenously.[1-4] Use during and after cesarean section appears to not affect the onset of breastfeeding.[1,5] No adverse infant effects have been reported in this setting or among women who received ondansetron postpartum in a pharmacokinetic study. Use of ondansetron in nursing mothers beyond the immediate postpartum setting has not been studied well, but the drug is labeled for use in infants as young as 1 month of age. A computer model demonstrated that the amounts in milk are much less than this dose. No special precautions are required.

“Summary of Use during Lactation”, LactMed record “Ondansetron” (LM1219), quoted verbatim. Everything LactMed reports about Ondansetron while breastfeeding.

Nursing Mothers Ondansetron is excreted in the breast milk of rats. It is not known whether ondansetron is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ondansetron is administered to a nursing woman.

Prescribing label, section “Nursing Mothers”: ondansetron (oral), Bryant Ranch Prepack. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.