Ondansetron dose
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ondansetron dosing adults children indications
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Ondansetron Dosing
Ondansetron is a 5-HT₃ receptor antagonist used for nausea and vomiting (PONV, chemotherapy-induced, radiation-induced, and general nausea).
Adults
| Route | Dose | Frequency |
|---|---|---|
| Oral | 8 mg | Every 8–12 hours |
| IV / IM | 4 mg | Every 4–8 hours PRN |
| IV (CINV, chemo) | 8 mg or 0.15 mg/kg | 30 min before chemo; repeat at 4 & 8 hrs |
| Oral (PONV prophylaxis) | 16 mg | 1 hour before anesthesia |
| IV (PONV treatment) | 4 mg | Single dose |
Children (≥6 months)
| Route | Dose | Max per dose |
|---|---|---|
| Oral or IV | 0.15 mg/kg | 8 mg |
| Frequency | Every 8–12 hours PRN | — |
Key Safety Notes
- QT prolongation: Ondansetron prolongs the QT interval. Avoid or use with caution alongside other QT-prolonging drugs (e.g., haloperidol, methadone, fluoroquinolones). Monitor with ECG when risk is high.
- Serotonin syndrome: Risk when combined with other serotonergic agents.
- Hepatic impairment: Max daily dose of 8 mg in severe hepatic impairment (Child-Pugh C).
- IV dose limit: Single IV doses >32 mg are contraindicated due to QT risk.
- Do not use the 32 mg single IV dose (withdrawn from market in many countries due to cardiac risk).
Dosing per Clinical Management and Infection Prevention and Control guidelines (p. 135) and standard pharmacology references.
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