Chemotherapy is the use of drugs to kill bacteria, viruses, fungi, and cancer cells. Most commonly, the term is used to refer to cancer-killing drugs. This article focuses on cancer chemotherapy.

Chemotherapy drugs can be given by mouth or injection. Because the medicines travel through the blood stream to the entire body, chemotherapy is considered a body-wide (systemic) treatment.

Chemotherapy may be used to:

• Cure the cancer
• Keep the cancer from spreading
• Ease symptoms (when the cancer cannot be cured)

Chemotherapy medicines usually target cells that quickly divide. However, normal cells -- including those found in the blood, hair, and the lining of the gastrointestinal tract -- also divide very quickly. That means chemotherapy can also damage or kill these healthy cells. When this occurs, side effects such as nausea, anemia, and hair loss can occur. Some persons who receive chemotherapy also have fatigue, nerve pain, and infection.

Side effects of chemotherapy depend on many things, including the type of cancer and specific drugs being used. Newer chemotherapy drugs that better target cancer cells may cause fewer side effects.