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Side Effects

Understanding Nausea and Vomiting

Many people with cancer will have nausea and vomiting. These symptoms are most often side effects of cancer treatment but can also have other causes.  

  • Nausea is feeling queasy, sick to your stomach or as if you might throw up.
  • Vomiting is throwing up the food and liquid in your stomach.  Nausea can lead to vomiting, and sometimes nausea and vomiting happen at the same time. But they can be totally separate problems, too.  
  • Retching is trying to vomit but nothing comes up from your stomach. This is also called gagging or dry heaves.


Types of nausea and vomiting in people with cancer

Acute nausea and vomiting happen minutes to hours after treatment is given. It usually goes away within a day.

Delayed nausea and vomiting start more than 24 hours after treatment and can last for a few days. This happens most often with certain types of chemotherapy, such as cisplatin, carboplatin, cyclophosphamide (Cytoxan) or anthracyclines such as doxorubicin.

Anticipatory nausea and vomiting happen before a treatment begins. This happens when a person comes across sights, sounds, and smells that their brain connects with nausea and vomiting. This happens most often in people whose nausea and vomiting were not well controlled during prior treatments.

Breakthrough nausea and vomiting happen even though treatment has been given to try to prevent it. When this happens, you may need more or other medicines to control current symptoms. And your cancer care team probably will need to change the medicines they give you for future treatments.

Refractory vomiting is what happens when the medicines you’re getting to prevent or control nausea and vomiting are not working. This means you may need more or different medicines to stop the nausea and/or vomiting.

What causes nausea and vomiting in people with cancer?

Nausea and vomiting in people with cancer can be caused by many things, such as:

  • Cancer treatment such as chemotherapy, radiation therapy, targeted drug therapy, or immunotherapy
  • Cancer that affects the brain or abdomen (belly)
  • Medicines used to help with side effects of cancer or treatment
  • Medicines given for other health problems
  • Bowel slowdown or blockage (obstruction)
  • Constipation
  • Infections
  • Anxiety
  • Pain
  • Dehydration

Not all people who get treated for cancer have nausea and/or vomiting. Your risk for having nausea or vomiting depends on the type of cancer being treated and the type of treatment and dose being given.

Symptoms of nausea and vomiting

People with nausea may feel queasy, sick to their stomach and as if they might throw up.

Having nausea and vomiting can also lead to other symptoms, such as:

Some of these symptoms are caused by dehydration or not having enough fluid in the body. If nausea and vomiting continue, you might not be able to take in enough fluid and food to meet your body’s need. Let your cancer care team know if:

  • You can’t keep fluids down
  • You’re vomiting for 24 hours or longer

Nausea and vomiting can affect a person’s quality of life. It can cause distress and may make a person wonder if they can continue treatment. For most people, nausea and vomiting can be controlled with medicines and other treatments that don’t include medicines. Talk with your doctor or cancer care team about what can be done to prevent and manage any nausea and vomiting your treatment might cause.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.


American Society of Clinical Oncology. Nausea and vomiting. Accessed March 6, 2024.

Freedman K & Hole A. Gastrointestinal complications. In: Eggert JA, Byar KL & Parks LS, ed. Cancer Basics. Oncology Nursing Society; 2022: 313-331.

Hesketh PJ et al. Antiemetics: ASCO guideline update. Journal of Clinical Oncology. 2020;38(24). Accessed at on March 11, 2024.

Mathey K. Nausea and vomiting. In: Camp-Sorrel D, Hawkins RA, Cope DG, eds. Clinical Manual for the Advanced Practice Nurse. Oncology Nursing Society; 2022: 509-515.

National Cancer Institute (NCI). Nausea and Vomiting Related to Cancer Treatment (PDQ) – Health Professional Version. Accessed at on March 8, 2024.

National Comprehensive Cancer Network (NCCN). Antiemesis. Version 1.2024. Accessed at on March 6, 2024.


Last Revised: June 26, 2024

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