Ondansetron is a medicine that prevents and treats nausea and vomiting. Doctors often prescribe it for people who have chemotherapy, radiation therapy, or surgery. It also helps with vomiting from stomach infections.
What Is Ondansetron Used For?
- Nausea and vomiting caused by chemotherapy and radiation
- Nausea and vomiting after surgery
- Severe vomiting from stomach infections, when a doctor prescribes it
- Severe nausea during pregnancy, when other treatments fail
How Does Ondansetron Work?
Ondansetron blocks serotonin 5-HT3 receptors in the gut and in the brain area that triggers vomiting. This stops the signal that makes you feel sick.
General Dosage Information
This is general information only. Your doctor sets the right dose for you, so follow your prescription and the label.
- Adults commonly take 4 mg to 8 mg every eight hours. Before chemotherapy, doctors may give 8 mg.
- Dissolving tablets melt on the tongue and do not need water.
- Doctors dose children by weight.
Side Effects of Ondansetron
Common Side Effects
- Headache
- Constipation
- Tiredness
- Dizziness
Serious Side Effects
Call your doctor or get emergency help if you notice:
- Fast, irregular heartbeat, or fainting
- Agitation, fever, and muscle stiffness, which can signal serotonin syndrome
- Swelling of the face or trouble breathing
- Yellow skin or eyes
Who Should Be Cautious?
- People with heart rhythm problems or low potassium or magnesium
- People with severe liver disease, who need a lower dose
- Pregnant women should ask their doctor, especially in the first three months
Drug Interactions
Tell your doctor and pharmacist about every medicine and supplement you take. Examples of important interactions include:
- Apomorphine: do not combine them.
- Medicines that affect heart rhythm, such as amiodarone: they raise the risk of dangerous rhythm problems.
- Tramadol and antidepressants: they raise the risk of serotonin syndrome.
- Phenytoin and carbamazepine: they can lower ondansetron levels.
Storage and Precautions
- Store it at room temperature, away from heat, light, and moisture.
- Keep it out of the reach of children.
Frequently Asked Questions
When should I take it before chemotherapy?
Doctors usually advise taking it 30 minutes before chemotherapy. Follow their instructions.
Does it cause constipation?
It can. Drink fluids and eat fiber.
Can I take it on an empty stomach?
Yes. You can take it with or without food.
Disclaimer: This article is for information only. It is not medical advice. Please talk to your doctor about your own health.