This is the third article in a three-part series, and it describes side effects of radiation therapy. Other articles in this series provide an overview of radiation therapy—including the various types—and explain what to expect when receiving radiation therapy.

Although it is an effective treatment for many types of cancer, radiation therapy—like other cancer treatments—can cause side effects. These vary from person to person and with the type and location of cancer, the treatment dose, and the person's health.

Side effects associated with radiation therapy may occur because the high doses of radiation used to kill cancer cells can also damage healthy cells around the treatment area. However, major improvements in radiation technology have made it more precise, resulting in fewer side effects.

For some people, radiation therapy causes few or no side effects. For others, the side effects are more severe. The reactions often begin by the second or third week of treatment and may last for several weeks after the final radiation treatment. Your health care team will work with you to ease or prevent many of these side effects.

Common side effects of radiation therapy

Many people who receive radiation therapy experience skin problems, such as dryness, itching, blistering, or peeling. These issues are usually resolved within a few weeks after treatment is finished. If skin damage from radiation treatment becomes a serious problem, the doctor may change the dose or schedule of treatments.

Another common side effect is fatigue (lack of energy). Fatigue associated with cancer treatment differs from fatigue from lack of sleep; it is a feeling of exhaustion that does not improve with rest. Your level of fatigue may depend on whether are undergoing other treatments, such as chemotherapy, as well. Learn more about coping with cancer-related fatigue.

Depending on which part of your body receives radiation therapy, other side effects may include:

• Diarrhea
  
  
• Nausea and vomiting
  
  
• Dry mouth
  
  
• Trouble swallowing
  
  
• Swelling
  
  
• Hair loss
  
  
• Sexual problems
  
  
• Urinary and bladder changes

Although most side effects go away after treatment, some long-term side effects may occur months or even years after treatment. These include secondary cancers; however, the risk of developing a secondary cancer because of radiation therapy is low and that risk is generally outweighed by the benefit of treating the primary, existing cancer.

Site-specific side effects

In addition to the side effects described above, some side effects of radiation therapy depend on where the radiation is given.

Head and neck. Side effects of radiation therapy to the head and neck may include dry mouth, difficulty swallowing, mouth and gum sores, stiffness in the jaw, and nausea.

In addition, tooth decay can occur. Before beginning radiation therapy for any head and neck cancer, visit an oncologic dentist (a dentist experienced in treating people with head and neck cancer). This dentist may recommend removing teeth before beginning treatment to help prevent osteoradionecrosis (jaw disease) and may prescribe a special fluoride treatment to help prevent tooth decay. Learn more about dental health during cancer treatment.

Meanwhile, radiation therapy can sometimes cause a type of swelling called lymphedema. Learn more about head and neck lymphedema.

Chest. Side effects from radiation therapy to the chest may include difficulty swallowing, cough, fever, shortness of breath, breast or nipple soreness, and shoulder stiffness. Some people may develop a cough, fever, and fullness of the chest that is diagnosed as radiation pneumonitis, an inflammation of the lung occurring between two weeks and six months after radiation therapy. Left untreated, radiation pneumonitis could cause radiation fibrosis (inflammation of the lungs from radiation), which is associated with more serious heart and lung problems. Radiation lung fibrosis (permanent scarring of the lungs from radiation) can occur, as well. The dose of radiation associated with fibrosis is well known and the radiation oncologist accounts for this in the planning process to minimize symptoms from fibrosis.

Stomach and abdomen. Side effects from radiation therapy to the stomach and abdomen may include nausea, vomiting, or diarrhea. These symptoms will likely disappear when treatment is completed. Your doctor can prescribe medications for these side effects, and changes to your diet can also reduce your discomfort. Read more about diet and nutrition while living with cancer.

Pelvis. Side effects from radiation to the pelvis may include digestive problems and bladder irritation. Drinking fluids—other than alcohol or caffeinated drinks—can help prevent dehydration associated with diarrhea.

In addition, radiation therapy can affect the reproductive system. Some women receiving high doses of radiation therapy may stop menstruating and experience symptoms of menopause, such as vaginal itching, burning, and dryness. Permanent infertility (the inability to conceive a child or maintain a pregnancy) can occur, generally only if both ovaries receive radiation. Men receiving radiation therapy to the testes or to nearby organs, such as the prostate, will have lowered sperm counts and reduced sperm activity, which affects fertility (the ability to father a child). Learn more about fertility and cancer treatment.

Radiation therapy can lead to other sexual problems, as well, in both men and women. For instance, radiation to the prostate can result in impotence (the inability to maintain an erection). Learn more about sexual side effects.

Meanwhile, radiation to the prostate may affect the functions of the rectum, bladder, and penis. Side effects may include diarrhea, rectal bleeding, incontinence, and impotence, as stated above.

More Information

Managing Side Effects

Frequently Asked Questions About Radiation Therapy

Additional Resources

National Cancer Institute: Radiation Therapy Side Effects

RT Answers: Side Effects

Last Updated: July 12, 2010