Is Zofran (Ondansetron) Safe for Breastfeeding?
Yes, ondansetron is safe and compatible with breastfeeding according to current anesthesia guidelines, and you can use it when clinically indicated for nausea and vomiting without requiring any waiting period or pumping-and-dumping. 1
Guideline-Based Recommendations
The Association of Anaesthetists explicitly recommends ondansetron as a safe anti-emetic option for breastfeeding women based on expert consensus from this major specialty society. 1 This recommendation applies to:
- Full-term, healthy, exclusively breastfed babies from mothers taking standard recommended doses 1
- No special precautions needed regarding timing of breastfeeding 1
- No pumping-and-dumping required when using ondansetron 1, 2
Supporting Evidence from Research
The most recent and highest quality study provides strong reassurance:
- A 2022 physiologically-based pharmacokinetic model using prospectively collected data from 78 breastfeeding women in the CUDDLE study demonstrated that the relative infant dose (RID) of ondansetron is only 3.0%, well below the 10% safety threshold. 3
- The calculated daily infant dose was extremely low at 0.005 mg/kg/day. 3
- The study authors concluded that mothers receiving ondansetron can safely breastfeed. 3
FDA Drug Label Information
The FDA label acknowledges limited human data but notes important context:
- It is not known whether ondansetron is present in human milk, though animal studies show it is present in rat milk. 4
- The label recommends considering "the developmental and health benefits of breastfeeding along with the mother's clinical need for ondansetron tablets and any potential adverse effects." 4
Clinical Approach
When prescribing ondansetron to breastfeeding mothers:
- Use ondansetron when clinically indicated for nausea/vomiting without hesitation 1
- Standard dosing applies (typically 4-8 mg as needed) 1
- Continue breastfeeding normally without timing restrictions 1
- No monitoring of the infant is required given the extremely low exposure 3
Important Context
The guideline evidence takes precedence here over the FDA's cautious "unknown" statement, as the FDA label predates the 2022 CUDDLE study and the 2025 guideline recommendations. 1, 3 The Association of Anaesthetists guidelines represent current best practice based on accumulated clinical experience and emerging research. 1
Ondansetron is actually recommended as a safer alternative to other anti-emetics (like promethazine) that carry theoretical risks of infant sedation. 2