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Supportive Care

Brand names:


Other names:

Ondansetron Hydrochloride

Often used for:

treating nausea and vomiting

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About Ondansetron

Ondansetron is medicine used to prevent or treat nausea and vomiting caused by chemotherapy, radiation therapy, surgery.

Patients may differ in how slowly or quickly their body breaks down ondansetron due to the function of a certain enzyme called P450 2D6 (CYP2D6). A genetic test may be performed to see how a patient’s enzymes function. This medicine may not work well in patients who break down ondansetron faster than normal.

This medicine is typically given 30 minutes before the start of chemotherapy.

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May be taken as a tablet or dissolvable film or tablet by mouth

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May be taken as a liquid by mouth

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May be given as a liquid into a vein by IV or injection

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Possible Side Effects

  • Headache
  • Abdominal pain
  • Dizziness
  • Diarrhea
  • Constipation
  • Rash
  • Fatigue or weakness
  • Blurred vision
  • Anxiety
  • Heart problems
  • Liver problems

Not all patients who take ondansetron will experience these side effects. Common side effects are in bold, but there may be others. Please report all suspected side effects to your doctor or pharmacist.

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Tips for Families

Be sure to discuss these and other recommendations with your doctor or pharmacist.

Ondansetron at home:

  • Non-dissolvable tablets should be swallowed whole. Do not crush or chew before swallowing.
  • Dissolvable tablets or film should be placed on the tongue and allowed to melt with saliva. Do not chew or swallow with water or other liquid. Make sure hands are dry when handling the medicine. 
  • For liquid ondansetron, use the measuring device that comes with the medicine.
  • Give a missed dose as soon as possible. If it is near the time for the next dose, skip the dose. Do not give 2 doses at the same time.
  • Store ondansetron at room temperature. Ondansetron for IV infusion should be stored in the refrigerator.
  • Do not use the medicine past the expiration date.
  • Follow instructions for disposal.