Ondansetron (Zofran) Safety During Breastfeeding
Ondansetron is safe and compatible with breastfeeding and can be used 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 when ondansetron is clinically indicated for nausea and vomiting, with no special precautions needed regarding timing of breastfeeding. 1
Key Safety Data
The calculated relative infant dose is only 3.0%, well below the 10% safety threshold typically used to assess medication compatibility with breastfeeding. 2 A physiologically-based pharmacokinetic model using data from 78 breastfeeding women demonstrated that:
- The daily infant dose is approximately 0.005 mg/kg/day 2
- This low exposure level indicates mothers receiving ondansetron can safely breastfeed 2
- Model predictions showed good agreement with observed breast milk and plasma concentrations 2
FDA Labeling Information
The FDA label acknowledges that it is unknown whether ondansetron is present in human milk, though animal studies demonstrate ondansetron is present in rat milk. 3 The label states that when a drug is present in animal milk, it is likely present in human milk, and recommends considering the developmental benefits of breastfeeding along with the mother's clinical need for ondansetron. 3
Clinical Context
Most commonly used drugs are relatively safe for breastfed babies, as the dose received via milk is generally small and much less than known safe doses given directly to infants. 4 Ondansetron is frequently requested by breastfeeding women experiencing nausea and vomiting, particularly those with hyperemesis gravidarum while nursing an older infant. 5
Important Caveats
- The guideline recommendations apply to full-term, healthy, exclusively breastfed babies from mothers taking standard recommended doses 6
- While ondansetron presence in human milk is technically "unknown" per FDA labeling, the pharmacokinetic modeling and clinical experience support its safety 3, 2
- Restrictive product information may cause unnecessary anxiety about breastfeeding continuation, but evidence-based resources support ondansetron use 5