Ondansetron stops nausea and vomiting. It is effective, but it treats the symptom only — in a stomach infection, rehydration is still what actually matters.
- Generic name
- Ondansetron hydrochloride
- Active ingredient
- Ondansetron hydrochloride
- Common brands in India
- Emeset, Ondem, Vomiraf, Zofer, Emset
- Available as
- Tablet, Mouth-dissolving tablet, Syrup, Injection
- Common strengths
- 4 mg, 8 mg, 2 mg/5 mL syrup
- How it is sold
- Prescription only — needs a doctor's prescription
No dosage information on this page
The correct dose depends on your age, weight, kidney and liver function, other medicines and medical history. Follow the dose your doctor prescribed, or the instructions on the pack. Never copy a dose from a website or from someone else's prescription.
What Ondansetron is used for
- Nausea and vomiting caused by chemotherapy or radiotherapy
- Nausea and vomiting after surgery
- Severe vomiting from a stomach infection, when a doctor decides it is needed
- Some cases of severe vomiting in pregnancy, only under specialist advice
How it works
Vomiting is triggered by serotonin signals sent from the gut and the brain to the part of the brain that controls the reflex. Ondansetron blocks those signals, which is why it works well for nausea that other medicines do not touch.
How to take Ondansetron
- The mouth-dissolving tablet is placed on the tongue and left to dissolve — do not swallow it whole with water. Handle it with dry hands.
- Ordinary tablets can be taken with or without food.
- Keep drinking small sips of oral rehydration solution even once the vomiting settles. Stopping the vomiting is not the same as replacing what was lost.
- Use it for the short period your doctor advised rather than keeping it as a standing remedy at home.
Precautions
- Tell your doctor about any heart rhythm problem, or a family history of sudden cardiac death.
- Tell your doctor about liver disease and about all your other medicines — several interact with it.
- Constipation is common. Keep fluids up once you are able to.
- It relieves the symptom without treating the cause. Vomiting that continues, or comes with severe pain or blood, needs a doctor.
Common side effects
Not everyone gets side effects. Tell your doctor if any of these are troublesome or do not settle.
- Headache
- Constipation
- Tiredness
- Flushing or a warm feeling
- Changes in the heart's electrical rhythm, seen on an ECG rather than felt
Important warnings
- In gastroenteritis, dehydration is what makes people seriously ill, not the vomiting itself. Oral rehydration solution is the treatment. An anti-vomiting tablet can make ORS easier to keep down, but it is not a substitute for it.
- Get medical help for vomiting with severe stomach pain, blood in the vomit, a stiff neck with fever, confusion, or signs of dehydration such as very little urine, sunken eyes or extreme drowsiness.
- It can affect the heart's electrical rhythm, particularly at higher amounts, in people with existing heart conditions, or alongside certain other medicines.
- Do not use leftover ondansetron for a future illness, and do not give it to a child unless a doctor has prescribed it for that child.
Frequently Asked Questions
Does ondansetron treat food poisoning?
No. It stops the vomiting, which can make you feel considerably better and makes it possible to keep fluids down, but it does nothing to the infection itself. What actually treats you is rehydration — oral rehydration solution, in small frequent sips.
How quickly does ondansetron work?
Usually within about half an hour of a tablet, and faster by injection. If vomiting continues despite it, that is a reason to see a doctor rather than to take more.
Is ondansetron safe in pregnancy?
It is sometimes used for severe vomiting in pregnancy, but only on specialist advice. There has been debate about its use in the first three months, so this is firmly a decision for your doctor rather than something to take from a leftover strip at home.
What are the side effects of ondansetron?
Headache and constipation are the common ones, along with tiredness and flushing. It can also affect the heart's electrical rhythm, which is why it is prescribed rather than sold as a routine home remedy.
What this costs, and what is free
Commonly available free at government hospitals and health and wellness centres when prescribed there.
Generic versions are sold at Jan Aushadhi Kendras at substantially lower prices than branded packs of the same medicine.
The same molecule is sold under many brand names at very different prices. Ask your doctor to write the generic name, and compare at a Jan Aushadhi Kendra — the saving on a medicine taken daily is often substantial over a year. You can look up any medicine's official ceiling price on NPPA's Pharma Sahi Daam app.
Source: Pradhan Mantri Bhartiya Janaushadhi Pariyojana (PMBJP), National Pharmaceutical Pricing Authority (NPPA)
Prices and scheme rules change. Confirm current details with the hospital or Kendra before you rely on them.
Looking for Ondansetron locally?Aswini Medicals is a pharmacy that stocks everyday medicines and can advise on availability.
Visit Aswini Medicals