Ondansetron is used to prevent or treat nausea and vomiting. Learn how to use the medication, its common side effects, special precautions to watch out for, and more.

What is this medication for?

Ondansetron is used to prevent or treat nausea and vomiting. Ondansetron works by blocking the actions of a chemical called serotonin that causes nausea and vomiting. 

For use of Ondansetron for nausea and vomiting in pregnancy, please click here: Nausea and Vomiting Medications in Pregnancy (healthhub.sg)

How should I take or use this medication?

You may take Ondansetron with or without food. 

What should I do if I forget to take or use this medication?

• Ondansetron is generally taken on an as-needed basis. Take them regularly only when directed by the doctor. 
• If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose. 

What precautions should I take when taking or using this medication?

Inform your healthcare professional if: 

• You are allergic to this medication or any of the other ingredients of this medication
• You have a history of:
• Liver condition
• Abnormal heart rhythm
• Recent surgery in the stomach area
• You are pregnant or breastfeeding 
• You are taking any other medications, including supplements, traditional medications and herbal remedies. 

What are some common side effects of this medication?

• Constipation
  • Drink more water (unless you are on fluid restriction) and eat more high fibre food such as fruits and vegetables.
• Diarrhea
  • Ensure adequate hydration 
• Headache
• Drowsiness 
  • Avoid driving or engaging in activities that require concentration
•        Anxiety

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following:

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately:

• Trouble passing urine
• Sudden chest pain or tightness
• Fast or abnormal heartbeats

Ondansetron is generally safe, but very rarely a serious condition known as Serotonin syndrome may occur. This can cause serious health problems that may sometimes be life threatening. This condition can occur when taking Ondansetron together with certain medications that can cause a chemical called serotonin to build up in the body.

Stop this medication and see a doctor immediately if you have the following signs of serotonin syndrome: Confusion, excessive sweating, shaking, hallucinations (sees, hears or feels something that is actually not there), muscle stiffness, seizures, severe diarrhea, or headache.

What food or medication should I avoid when I take or use this medication?

Inform your doctor if you are taking:     

• Certain heart medications (e.g. Amiodarone, Sotalol)
• Domperidone which is used for treating nausea and vomiting
• Apomorphine, which is used for treating Parkinson’s disease

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How do I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin. 

Disclaimer

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Oct 2024