Ondansetron
Zofran is the only ondansetron product on this page, a tablet in 4 mg and 8 mg strengths for preventing nausea and vomiting after chemotherapy or surgery.
Key points
- Do not take ondansetron with apomorphine, a Parkinson’s disease medicine; the combination is a stated contraindication.
- The label warns against ondansetron in people with congenital long QT syndrome, and calls for ECG monitoring when other QT-prolonging drugs are taken at the same time.
- Serotonin syndrome has been reported with ondansetron, particularly when taken alongside other serotonergic medicines.
How does Ondansetron work?
Ondansetron blocks 5-HT3 receptors in the gut and the brain’s vomiting centre. When chemotherapy or surgery triggers serotonin release, those receptors send a signal that makes you feel sick and vomit; ondansetron stops that signal from getting through. Because it works specifically on the serotonin pathway, it does not address nausea from other triggers such as motion sickness. Ondansetron is listed under Oncology Support for its role in managing chemotherapy side effects.
Further reading
What is ondansetron used for?
Ondansetron is used to prevent nausea and vomiting after chemotherapy or surgery.
How does ondansetron stop nausea and vomiting?
Ondansetron blocks 5-HT3 receptors in the gut and the brain's vomiting centre. It stops the signal that makes you feel sick and vomit when chemotherapy or surgery triggers serotonin release. It does not address nausea from other triggers such as motion sickness.
How long does ondansetron take to work?
Ondansetron starts to work within 30 to 60 minutes. Its effect lasts for 8 to 12 hours.
What are the side effects of ondansetron?
Common side effects of ondansetron include headache, constipation and fatigue. Serious side effects that need immediate medical attention are QT prolongation and serotonin syndrome. Talk to your doctor or pharmacist if you notice any side effects.
Can ondansetron be taken with other medicines?
Ondansetron should not be taken with apomorphine, a Parkinson's disease medicine, and ECG monitoring is needed when other QT-prolonging drugs are taken at the same time. Serotonin syndrome has been reported when ondansetron is taken alongside other serotonergic medicines, so speak to your doctor or pharmacist before combining it with other medicines.
What ondansetron products are available?
On Direct Meds, ondansetron comes as Zofran. Compare their forms, strengths and packs.
How much does ondansetron cost in South Africa?
Compare the rand prices for each product, strength and pack above. Prices are converted from US dollars. Larger packs usually cost less per tablet.
Payment and prices →Is ondansetron available over the counter in South Africa?
Yes, online. Direct Meds does not ask for a prescription to order ondansetron. We are a broker, not a dispensing pharmacy. We arrange orders and delivery with our affiliated supplier on your behalf.
Ordering without a prescription →Where can I buy ondansetron in South Africa?
On Direct Meds: choose the product, strength and pack, then check out. Our affiliated supplier delivers across South Africa. Estimated delivery is 7 days with Express Delivery, which includes online tracking, or up to 3 weeks with Regular Delivery.
How ordering works →