Ondansetron is a drug that belongs to a class of drugs known as selective 5-HT3-receptor antagonists. It blocks serotonin in the brain and nerves and this prevents vomiting in chemotherapy.

Ondansetron is used in the treatment of the following:

  • Nausea and vomiting associated with cancer chemotherapy
  • Nausea and vomiting associated with radiation therapy

Do not use in patients with congenital long QT syndrome. This drug should not be concomitantly used with apomorphine.

Ondansetron can give rise to the following side effects:

  • Headache
  • Hiccups
  • Flushing or warmth sensation
  • Constipation
  • Rash
  • Urticaria
  • Seizures and movement disorders including extrapyramidal symptoms (e.g. dyskinesia, dystonia, oculogyric crisis)
  • Injection site reaction
  • Dizziness
  • Transient visual disturbances (blurred vision or very rarely, transient blindness)
  • Local burning sensation
  • Transient liver enzyme elevation
  • Anaphylaxis
  • Bradycardia
  • Tachycardia, arrhythmia
  • Chest pain
  • Hypotension
  • Transient ECG changes
  • Torsade de pointes


Take extra caution in the following conditions:

  • Progressive ileus and/or gastric distension
  • Severe liver disease
  • Pregnancy and lactation



Ondansetron may interact with the following medicines:

  • Tramadol
  • Rifampicin and other CYP3A4 inducers
  • QT-prolonging agents (e.g. antiarrhythmics)
  • Cardiotoxic drugs (e.g. anthracyclines)
  • Apomorphine

Symptoms of overdose include the following:

  • Severe constipation
  • Visual disturbances
  • Hypotension
  • Vasovagal episode w/ transient 2nd degree AV block

Seek medical help immediately


Available Brand:

  • Zofran

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