Side effects
Nausea and vomiting
Nausea and vomiting are common with some cancer treatments, but today they can usually be prevented or well controlled with medicine.
Why it happens
Some chemotherapy drugs, radiation to the belly or brain, and other medicines can trigger nausea and vomiting. Nausea may start within hours of treatment or a few days later. Whether you have it depends on the treatment, the dose, and your own history, such as motion sickness or nausea during pregnancy.
What helps
- Take your anti-nausea medicine as prescribed, including before and after treatment, even if you feel fine. It is easier to prevent nausea than to stop it.
- Eat small meals often, and don’t skip meals. An empty stomach can make nausea worse.
- Choose plain, bland foods such as toast, crackers, rice or broth, and avoid greasy, spicy or very sweet foods.
- Sip fluids throughout the day, between meals rather than with them.
- Avoid strong smells, and get fresh air when you can.
- Try relaxation, such as slow breathing, music or distraction.
When to call your care team
Call if you vomit more than a few times in a day, can’t keep liquids or medicines down for 24 hours, see blood or what looks like coffee grounds in your vomit, or feel dizzy or very weak, which can be signs of dehydration.
Questions to ask your care team
Bring these to your next visit, or write down your own.
- Which anti-nausea medicines should I take, and when?
- What should I do if the medicine isn't working?
- Are there foods I should eat or avoid?
- How do I know if I'm getting dehydrated?
Go deeper
More detailed information
For more clinical detail, our affiliate, Northside Hospital Cancer Institute, covers this topic in depth.
Nausea and vomiting (National Cancer Institute)Sources
This page is for general education and does not replace advice from your doctor or care team. Last updated October 26, 2026.