What Is It?

Chemotherapy drugs are medicines used to kill cancer cells and to prevent cancer from spreading. These drugs are also called anti-cancer drugs or chemotherapeutic agents. There are more than 80 anti-cancer drugs available, with many more being studied. Each type of anti-cancer drug works in a slightly different way. In general, they all kill cancer cells, or interfere with the ability of cancer cells to divide and grow. Disrupting the growth of the cells can limit the size of cancerous tumors. It can also prevent cancer from spreading to other parts of the body, such as to the bone, brain, liver or lungs.

Anti-cancer drugs come in many different combinations, and people using them follow many different treatment schedules. Each person’s chemotherapy plan depends on the cancer being treated and how far the cancer has spread. Most people receive anti-cancer drugs through a process called intravenous infusion. A bag filled with the liquid drug is attached to a tube that is inserted into a vein. The drug slowly “drips” into the patient’s body. Other people get their anti-cancer drugs from injections or in pill form.

Chemotherapy drugs reach almost all parts of the body. This helps to kill cancer cells that have spread from the original site of the cancer growth. The brain and the testes usually are exposed only to very low concentrations of chemotherapy. Cancers in these areas may be treated differently. The bad news is that anti-cancer drugs attack more than just cancer cells. Normal, healthy cells are destroyed as well, especially cells lining the mouth, digestive tract and hair follicles, and the blood cells within bone marrow. This is why many people receiving chemotherapy suffer mouth sores and upset stomachs, lose their hair and feel weak.

What It’s Used For

For some cancers, such as leukemia and multiple myeloma, chemotherapy is the primary form of treatment. For other cancers, chemotherapy is one part of a larger strategy that also involves radiation and/or surgery. Chemotherapy can destroy tumors or slow the growth of the cancer. Chemotherapy also can relieve symptoms and improve the quality of life for people with advanced cancer that cannot be destroyed or slowed.


Each type of anti-cancer drug produces its own set of side effects, which may be more or less severe depending on your body’s reaction to the drug. Always ask your doctor about the possible side effects of your anti-cancer treatment before chemotherapy begins.

How It’s Done

Anti-cancer drugs can be given in a hospital, clinic, doctor’s office or even at home. Sometimes the treatment is as easy as swallowing a pill; other times it requires an injection or a more complicated procedure in which the drugs are delivered slowly through intravenous infusion. People can receive chemotherapy daily, weekly or monthly. Sometimes there is a rest period between sessions. This allows the body to recover from side effects before the next wave of treatment begins.


Doctors use different tests to judge how well chemotherapy is working: physical exams, magnetic resonance imaging (MRI) and computed tomography (CT) scans, X-rays and laboratory tests that examine blood cells and blood chemistry.


Anti-cancer drugs can cause many side effects. Common ones include fatigue, nausea and vomiting, diarrhea, mouth sores, hair loss, rashes, and low levels of several different types of blood cells. Blood-cell problems may increase your risk of infections and bleeding. Your doctor has methods to decrease the severity of many of these side effects. Other side effects depend on the specific anti-cancer drugs used, and include allergic reactions, numbness and tingling in the hands and feet, irritation of the veins injected with the drug and bleeding from the bladder.

Because anti-cancer drugs can produce birth defects, particularly if used early in pregnancy, tell your doctor if you might be pregnant. Also, some chemotherapy drugs can cause infertility. Adults in their childbearing years should ask their doctors about the impact of chemotherapy on family planning.

When To Call A Professional

Call your doctor if you have any of the following problems during chemotherapy:

  • Fever
  • Chills
  • Rash
  • Swelling of your hands, feet or parts of your face
  • Severe vomiting
  • Diarrhea
  • Blood in your urine or bowel movements
  • Any abnormal bleeding or bruising in the skin
  • Trouble breathing
  • Severe headaches
  • Any unexplained pain that is severe or lasts for long periods

If anti-cancer drugs were injected, call your doctor if you develop pain, swelling or redness at the injection site.

Depending upon the type of chemotherapy, there may be other side effects to watch for. Your doctor will discuss them with you before treatment starts.

You might need some help adjusting your daily routine to deal with the side effects of chemotherapy. For example, if your anti-cancer treatment increases the effects of sunlight on your skin, you may need to change your schedule of outdoor activities or wear protective clothing and sun-blocking lotions. You might also need to stop taking certain medications, such as aspirin, cough medicine and sleeping pills, because they can interfere with some chemotherapy drugs. Your doctor can offer suggestions for minimizing the effects of chemotherapy.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.