Ondansetron
Ondansetron is a serotonin 5-HT3 antagonist used for selected nausea and vomiting.
Key points
- It treats symptoms but does not diagnose their cause.
- It can prolong QT and contribute to serotonin toxicity with interacting medicines.
- Fainting, irregular heartbeat or severe agitation with fever needs urgent care.
Select a listed product and pack to order online. Ask your doctor or pharmacist whether it suits you and what monitoring it needs.
Important safety checks
Cause of symptoms, heart rhythm, electrolytes, liver function and serotonergic medicines require review.
When to seek urgent care
Seek urgent help for fainting, a fast or irregular heartbeat, severe agitation with fever and rigidity, or a serious allergic reaction.
Further reading
What is ondansetron used for?
Ondansetron is an antiemetic used for nausea and vomiting. It eases these symptoms but does not treat their underlying cause.
How does ondansetron work?
Ondansetron blocks 5-HT3 receptors on the vagus nerve and in the brain's chemoreceptor trigger zone. This helps stop the nausea and vomiting that chemotherapy and surgery can bring on.
What ondansetron product does SGMeds list?
The ondansetron product on SGMeds is Zofran, and its page gives the strengths and pack sizes.
How long does ondansetron take to work?
Ondansetron usually starts working within 30 to 60 minutes, and the effect lasts 8 to 12 hours.
What are the side effects of ondansetron?
Common side effects include headache, flushing and constipation. Some people get dizziness, abdominal discomfort or a rise in liver enzymes. Serious effects like a heart rhythm change (QT prolongation), arrhythmia and a severe allergic reaction (anaphylaxis) need urgent medical attention.
Who should not take ondansetron?
It is not suitable if you are hypersensitive to it or if you are taking apomorphine. If you have a heart rhythm problem, low electrolytes, liver problems, or take serotonergic medicines, ask a doctor or pharmacist before using it.
How much does ondansetron cost in Singapore?
The product on this page shows a price for each strength and pack size in Singapore dollars, converted from US dollars, so the exchange rate can change the final amount. Larger packs usually cost less per tablet.
Payment and prices →Can I buy ondansetron over the counter in Singapore?
Yes, online. SGMeds does not ask for a prescription to order ondansetron: we place the order with our pharmacy partner, which prepares it and arranges delivery on your behalf.
Ordering without a prescription →Where can I buy ondansetron in Singapore?
You can order ondansetron here on SGMeds: choose the product, strength and pack, then check out. We deliver to Singapore and Malaysia. Express shipping is tracked and takes up to 1 week, and Regular shipping takes up to 3 weeks.
How ordering works →