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The Side Effects of Cancer Treatment

Chemotherapy and radiation treatments save lives. They also can bring a variety of temporary but unpleasant side effects. Ask your doctors about what side effects to expect, how to manage them, and what side-effect symptoms to report immediately. On office visits, make certain to tell your health care provider about the side effects you are experiencing. 

Many side effects of chemotherapy or radiation treatments occur for the same reason: The treatments kill cancer cells, but they also kill normal cells that are dividing quickly.


Chemotherapy essentially targets cells that divide frequently to wipe out the cells dividing out of control. In so doing, it also affects healthy cells that are dividing frequently. The effects vary greatly among the drugs used for chemotherapy, but in general these are most likely the cells to be affected:

  • Cells in the bone marrow

  • Red blood cells

  • Hair follicle cells

  • Cells found in the reproductive system

  • Cells in the stomach and intestines

Chemotherapy affects the cells in the bone marrow by reducing the number of white and red blood cells that are produced there. It also reduces the production of platelets, which are important in blood clotting. Bone marrow suppression is one of the most common effects of chemotherapy; this treatment also results in some suppression of the immune system. Because of this, while you are undergoing chemotherapy, your blood count will be closely monitored. When treatment stops, your blood count should return to normal.

Hair follicles on the scalp are frequently affected by chemotherapy. Hair can become brittle and break off, or fall out from the follicle. Some people lose all their hair; others end up with thinner hair. The hair on the eyebrows, eyelashes and skin, and in the pubic region may also be affected. When treatment stops, the hair will grow back.

Chemotherapy affects your nutrition in several ways. It often reduces appetite, which can lead to temporary anorexia. It also affects how food tastes, making mealtimes less enjoyable. Sores in the mouth and esophagus caused by chemotherapy may make eating painful.

In addition, nausea and vomiting are possible side effects, as well as diarrhea or constipation.

A person on chemotherapy also often experiences extreme tiredness called fatigue that's not related to physical activity. This fatigue may not ease with rest.

Other areas of the body that may be affected by chemotherapy:

  • Heart. Damage to the muscle of the heart can be a side effect of chemotherapy. Heart damage risk is increased if the person is a smoker, has existing heart disease or high blood pressure, or has had radiation therapy to the chest.

  • Brain and nervous system. Memory, comprehension, and reasoning skills may be affected. These effects may not show up for many years after treatment.

  • Lungs. Lung damage can be permanent and is more likely to occur in older people and in people who have had radiation therapy to the chest.

  • Reproductive system. Infertility may occur.

  • Liver. Liver damage occurs, but it is usually temporary.

  • Kidneys. The kidneys, ureters, and bladder may be damaged when chemotherapy drugs (or the metabolites) are excreted.

Radiation therapy

Radiation therapy is used to destroy cancer cells, but the radiation also can harm normal cells. Many people undergoing radiation therapy have no side effects from this, but others do.

The most common side effects are fatigue, skin changes at the site where the radiation enters and exits, and some loss of appetite. Other side effects usually are related to the treatment of specific areas, such as hair loss after radiation treatment to the head. Irradiation of the bone marrow affects the immune system and depresses blood cell and platelet counts. Radiation to the chest may cause difficulties swallowing, loss of chest hair, and skin changes on the chest. Radiation to the brain or digestive system may cause nausea, vomiting, or diarrhea.

Self-care tips

Chemotherapy doesn't always cause fatigue, flu-like illness, nausea, vomiting, diarrhea, or hair loss. Side effects depend on the medication used. Ask your doctor which side effects you can expect with the treatments you'll receive, then work with the doctor to minimize the possible symptoms. Be sure to write down the information you are given so you won't forget it.

For digestive-system symptoms:

  • Keep your mouth moist by drinking lots of water.

  • Avoid foods that irritate the mucous membranes, such as hot foods; foods with sharp edges, such as hard-crusted breads; or acidic foods, such as tomatoes or oranges.

  • Tell your doctor if you develop a sore spot in your mouth.

For nausea:

  • Drink plenty of fluids, even if you don't feel like eating. This will prevent dehydration and help your body eliminate the chemotherapy medication, which has already served its purpose. If you lose your appetite, drink fluids with calories, such as fruit juices, fruit smoothies, or chicken noodle soup.

  • Eat what appeals to you. Small, frequent meals are often better tolerated.

  • Choose easily digestible foods, such as mashed potatoes, pasta, rice, or cooked cereal.

For fatigue:

  • Prioritize your daily tasks, and try to do only necessary ones.

  • Delegate to others. Someone else may be able to do your shopping, so you can devote energy to other important concerns.

  • Pace yourself. Take plenty of rest breaks.

  • Set an alarm if you nap during the day, so you don't snooze too long. That could interfere with your nighttime sleep.

  • Engage in nonstrenuous physical activity, such as walking or yoga.

For hair loss:

  • Ask your health care provider to recommend a mail-order site with hats, scarves, and head wraps for cancer patients or a high-quality wig shop in your area. Match your hair color to a wig before hair loss starts. 

  • Avoid a sunburned scalp by wearing sunscreen or a head covering. Wear a warm hat in cold weather to retain body heat.

Alternative remedies

Various alternative treatments also may help relieve the symptoms of cancer therapy. The most useful options include nutrition, massage therapy, visualization, and stress-reduction techniques.

Talk with your health care provider about using these therapies in addition to your medical treatment. You should make sure those offering alternative treatments are licensed, certified, and experienced. Look for alternative health care providers providers who have experience working on a team with more conventional practitioners--and avoid any alternative therapists who say they can cure your cancer.