Antiemetic (anti-vomiting medicine)
Last reviewed June 2026
Who is this for?
Ondansetron is an anti-nausea medicine that works by blocking a chemical called serotonin in your body that triggers vomiting and nausea.
Blocks 5-HT3 (serotonin) receptors on vagal afferent nerves and in the chemoreceptor trigger zone, preventing nausea and vomiting signals from reaching the vomiting centre in the brainstem.
Prescription Required
You need a doctor's prescription to buy this drug.
Explore this drug
For adults, the usual dose is 4 mg to 8 mg taken by mouth two to three times daily depending on what your doctor prescribes. You can take it with or without food. If using the orally disintegrating tablet, place it on your tongue and let it dissolve — no need to swallow with water.
If you miss a dose, take it as soon as you remember. But if it's almost time for your next dose, skip the missed one and continue your normal schedule. Do not take two doses at once to make up for the one you missed.
Only buy from licensed pharmacies — avoid buying ondansetron from roadside sellers or unregistered shops as fake drugs are common in Nigeria. Do not use this medicine to treat ordinary stomach upset without a doctor's advice. If vomiting persists after using ondansetron, see a doctor — it could be a sign of something more serious.
Apomorphine (used for Parkinson's disease) should never be taken with ondansetron as it can cause a dangerous drop in blood pressure. Tramadol — ondansetron may reduce the pain-relieving effect of tramadol. Also be cautious if you are taking other medicines that affect heart rhythm, and mention all your medications to your pharmacist or doctor.
Check your specific combination
Is it safe to take Ondansetron with your other drugs?
Ondansetron should be used during pregnancy and breastfeeding only if your doctor says the benefit outweighs the risk — always consult your doctor before taking it if you are pregnant or nursing.
Store at room temperature, away from direct sunlight and heat — Nigerian weather can be very hot, so don't leave it in your car or near a window. Keep it in a cool, dry place away from moisture, and always keep it out of the reach of children.
For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under — especially in Nigerian and West African pharmacies
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Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.
Dispensing Ondansetron?
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