- Ondansetron helps prevent nausea and vomiting from chemotherapy, radiation therapy, and surgery by blocking serotonin’s effects.
- Available as tablets, orally dissolving tablets, and injections, with FDA-approved dosing for adults and children in specific situations.
- Common side effects include headache, dizziness, and constipation, while severe allergic reactions require immediate medical attention.
Ondansetron is an antiemetic used to prevent or treat nausea and vomiting, especially when they occur after chemotherapy, radiation therapy, or surgery. It works by blocking the action of serotonin, a chemical that can trigger the vomiting reflex.
This medication may also be labeled as ondansetron hydrochloride or ondansetron hydrochloride dihydrate. By reducing serotonin’s effect, it helps control both nausea and vomiting more effectively.
Ondansetron should only be used with medical guidance. In pharmacies, it is available as 4 mg and 8 mg tablets under the brand name Zofran. It can also be administered as an injection in hospital settings.
Indications for use
Ondansetron is recommended to prevent or treat nausea and vomiting caused by:
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Chemotherapy
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Radiation therapy
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Surgeries
Use should be guided by an oncologist or surgeon, with individualized dosing and regular follow-up.
How to take
The way ondansetron is taken depends on the formulation prescribed.
1. Oral ondansetron
Oral ondansetron is available as orally-dissolving tablets (ODT) and tablet forms.
ODT ondansetron should be removed from the blister and placed immediately on the tongue, where they dissolve within seconds. They do not need to be swallowed with liquids and should not be chewed or swallowed whole.
Film-coated tablets should be swallowed whole with a glass of water.
Dosing guidelines for oral ondansestron are the same for both forms:
2. Injectable ondansetron
Injectable ondansetron must be administered by a nurse or qualified health care provider into a vein or muscle in a hospital under medical supervision.
Typical adult doses include 8 mg given intravenously immediately before chemotherapy. Another option is 0.15 mg per kg intravenously every 4 hours for three doses.
For children 1 month to 17 years, injectable doses are based on body weight or body surface area according to physician calculation. Injectable ondansetron is FDA-approved for pediatric use.
Possible side effects
Common side effects include diarrhea, constipation, headache, dizziness, and fatigue.
More serious reactions can occur, such as difficulty breathing, chest pain, tightness in the throat, swelling of the face, lips, or tongue, or hives. Emergency care is necessary if these symptoms appear.
Since the injectable form is administered in hospitals, any severe reaction can be treated immediately.
Who should not use it
Ondansetron should not be taken by anyone with allergies to ondansetron or similar antiemetics such as dolasetron, granisetron, or palonosetron.
Ondansetron should not be used during the first trimester of pregnancy because of the potential risk of birth defects. In later trimesters, it should only be used if an obstetrician determines that the benefits outweigh the risks.
During breastfeeding, ondansetron should be taken only with medical advice, as small amounts may pass into breast milk.