Ondansetron

Written By Dr. Syeda Aafia

Reviewed By Dr. Rajeev Sharma

Last updated 25 Nov 2025 | 09:34 AM (UTC)

Ondansetron Uses

Ondansetron is used to prevent vomiting and nausea.

Available generics for Ondansetron

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Ondet 2mg Injection

vial of 10 ml injection

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How Ondansetron works

Ondansetron is an antiemetic medication. It works by blocking the action of a chemical messenger (serotonin) in the brain that may cause nausea and vomiting during anti-cancer treatment (chemotherapy) or after surgery.

Common side effects of Ondansetron

Constipation, Headache, Flushing (sense of warmth in the face, ears, neck and trunk), Injection site reactions (pain, swelling, redness)

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Medicine brands for Ondansetron

Ondem

Alkem Laboratories Ltd

Ipca Laboratories Ltd

₹12 to ₹88

6 variant(s)

Zofer

Sun Pharmaceutical Industries Ltd

₹12 to ₹96

9 variant(s)

Emigo

Zuventus Healthcare Ltd

₹12 to ₹54

6 variant(s)

Eterna

Blue Cross Laboratories Ltd

₹11 to ₹36

4 variant(s)

Emefilm

Delvin Formulations Pvt Ltd

₹281 to ₹309

2 variant(s)

Ondamac

Macleods Pharmaceuticals Pvt Ltd

₹39 to ₹53

2 variant(s)

Ontic

Corona Remedies Pvt Ltd

₹11 to ₹44

3 variant(s)

Expert advice for Ondansetron

You have been prescribed Ondansetron for prevention of nausea and vomiting caused after surgery or due to chemotherapy and radiotherapy.
It is fast-acting and starts working within 30 minutes.
If you vomit within one hour of taking a dose, take another dose.
Avoid heavy meals and try eating small nourishing snacks throughout the day. Also, sip water regularly to help avoid dehydration.
You have been prescribed Ondansetron for prevention of nausea and vomiting caused after surgery or due to chemotherapy and radiotherapy.
Unlike some other nausea medicines, the side effects for Ondansetron are relatively mild.
It comes in many different forms that do not need to be swallowed, such as a film that is placed on the tongue or as a dissolving pill.
It is fast-acting and starts working within 30 minutes.
If you vomit within one hour of taking a dose, take another dose.
Avoid heavy meals and try eating small nourishing snacks throughout the day. Also, sip water regularly to help avoid dehydration.

Frequently asked questions for Ondansetron

Q. How quickly does Ondansetron work?

Ondansetron starts working within half an hour to 2 hours. It dissolves rapidly into the bloodstream and starts showing its effect.

Q. What are the side effects of Ondansetron?

The most common side effects of Ondansetron are constipation, diarrhea, fatigue and headache. However, these are usually not bothersome and resolve on their own after some time. Consult your doctor if these persist or worry you.

Q. When should you take Ondansetron?

Ondansetron should be taken with a full glass of water, with or without food. It should be used exactly as per the dose and duration advised by the doctor. Usually, the first dose of Ondansetron is taken before the start of your surgery, chemotherapy or radiation treatment.

Q. Is Ondansetron a steroid?

No, Ondansetron is an antiemetic and not a steroid. Ondansetron is a selective 5-HT3 receptor antagonist. It is prescribed for the prevention and treatment of nausea and vomiting which is commonly observed after surgery or due to cancer chemotherapy.

Q. Does Ondansetron work for seasickness?

No, Ondansetron does not work for seasickness. This is because Ondansetron has very little effect on the nausea associated with motion sickness.