Ondansetron
Brand names: Zofran
Ondansetron is a 5-HT3 receptor antagonist antiemetic, used especially for nausea and vomiting related to chemotherapy, radiotherapy and surgery.
ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.
Clinical monograph
How it works
It blocks 5-HT3 (serotonin) receptors centrally and in the gut, dampening the vomiting reflex.
Prescribing in practice
- It prolongs the QT interval — use caution with other QT-prolonging drugs and in electrolyte disturbance, and avoid high single intravenous doses.
- Constipation and headache are common.
- Generally avoided in early pregnancy unless the benefit outweighs the risk (discuss).
Monitoring
Consider ECG and electrolytes where QT risk is high; review bowel habit.
Counselling the patient
- It can cause constipation and headache.
- Tell your clinician about other medicines, as some combinations affect heart rhythm.
Evidence & guidelines
A standard antiemetic for chemotherapy/radiotherapy and post-operative nausea and vomiting, with QT precautions.
Reference: MHRA Drug Safety Update 2013 (Ondansetron IV); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.