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Chemotherapy (chemo) is the use of drugs to kill cancer cells or shrink tumors. Usually the drugs are given into a vein or by mouth. Once the drugs enter the bloodstream, they spread throughout the body.

Chemo is often given along with radiation (chemoradiation) as the main treatment for more advanced cancers. Chemoradiation can also be used after surgery to try to lower the chance the cancer will come back.

Chemo is often used to ease symptoms of tumors that are too large or have spread too far to be completely removed.

Doctors give chemo in cycles, with each round of treatment followed by a rest time to allow the body to recover. Each chemo cycle typically lasts for a few weeks.

Possible side effects of chemotherapy

Chemo can have side effects. These side effects will depend on the type of drugs given, the amount taken, and how long treatment lasts. Common side effects are:

  • Nausea and vomiting
  • Loss of appetite
  • Hair loss
  • Mouth sores
  • Diarrhea (loose bowels)
  • A higher chance of infection (from a shortage of white blood cells)
  • Bleeding or bruising after minor cuts or injuries (caused by a shortage of blood platelets)
  • Tiredness and shortness of breath (from low red blood cell counts or from other things)

Along with the risks above, some chemo drugs can cause other side effects. Most side effects go away after treatment ends. If you have problems with side effects, talk with your doctor or nurse, as there are often ways to help.

To learn more about chemo, see the Chemotherapy section of our website.

Last Medical Review: 04/08/2014
Last Revised: 02/17/2016