Ondansetron
An antiemetic for nausea and vomiting. 4–8 mg in adults; 0.15 mg/kg in children. Check the QT.
On this page
Uses
- Nausea and vomiting: post-operative, gastroenteritis, chemotherapy, opioid-induced.
Adult dose
| Route | Dose |
|---|---|
| IV or oral | 4–8 mg up to every 8 hours (max 16 mg as a single IV dose) |
Children's dose
0.1–0.15 mg/kg (max 4 mg) IV or orally; single oral dose in gastroenteritis to allow ORS.
Kidney and liver
Severe liver disease: max 8 mg/day.
Pregnancy and breastfeeding
Can be used for severe vomiting in pregnancy after the first trimester or when other drugs fail (specialist advice in early pregnancy).
Side effects and cautions
- Constipation, headache.
- QT prolongation: caution with low potassium, magnesium or other QT drugs.
Frequently asked questions
What is the ondansetron dose for children with gastroenteritis?
A single oral dose of 0.15 mg/kg (max 4 mg), to help the child tolerate ORS.
Used in these guides
- Acute abdominal pain
- Acute pancreatitis
- Appendicitis
- Bowel obstruction
- Chest pain on the ward
- Diarrhoea and dehydration in children
- Eye injuries
- Eye problems: a structured approach
- Fractures and dislocations: the essentials
- Gastroenteritis in adults
- Hernias in the emergency department
- Minor head injury
- Ovarian torsion
- Post-operative complications
Sources
Doses on this page are typical doses from the sources above. Always confirm with a current drug reference, the product leaflet and your hospital protocol, especially in children, pregnancy and kidney or liver disease.