Side Effects of Radiation Therapy

It’s important to remember that the type of radiation side effects that you experience will depend on the type of cancer you have, the prescribed radiation dose and your general health. Because every patient reacts differently to treatment, some may experience a number of side effects while others experience few or none.

General side effects of radiation therapy

Fatigue. It’s very common for patients receiving radiation therapy to feel physically, mentally and emotionally exhausted. Fatigue often starts to set in after a few weeks of treatment and usually gets worse as treatment goes on. The fatigue felt during radiation therapy is different from everyday fatigue and may not go away with rest. While it can last a long time and may be disruptive to your usual routine, it usually goes away with time after treatment ends. Managing fatigue during radiation therapy is an important part of your care and your quality of life.

Skin problems. Radiation therapy may cause your skin to look red, swollen, blistered or tanned. Your skin may become dry, flaky or itchy after a few weeks of treatment, which is known as radiation dermatitis. These skin problems usually go away with time after treatment ends, though skin may sometimes be darker or more sensitive than it was before. It’s important to talk to your treatment team about any skin changes you experience – they will be able to suggest ways to lessen your discomfort and prevent infection.

Hair loss. Patients receiving radiation therapy may experience hair loss to the area being treated. Hair typically grows back after treatment ends, but it may be thinner or a different texture than it was previously. If you receive radiation to your head and lose your hair, your local American Cancer Society office may be able to help you get wigs or hats to protect your scalp. While it can certainly be difficult to deal with hair loss, your treatment team is here to address any questions or concerns you may have throughout your treatment.

Loss of appetite. Radiation therapy can cause problems like a dry or sore mouth, difficulty swallowing, nausea and vomiting, all of which can cause a loss of appetite. Some patients may lose interest in food and stop eating entirely, even though they know they need to. Maintaining good nutrition is a crucial part of radiation therapy and helping your recover from treatment. You may be referred to a nutritionist to help keep your body strong.

Fertility issues. Radiation therapy to the pelvic area can affect your ability to have a baby. It can sometimes cause women to stop having menstrual periods and experience other symptoms of menopause. For men, radiation to an area including the testicles can reduce the number of sperm as well as their ability to function. If you are concerned about reduced fertility, be sure to discuss this with your care team before beginning treatment.

Decreased libido or ability to enjoy sex. Both men and women may notice changes in their ability to enjoy sex or their sexual desire as a result of radiation therapy. For women receiving radiation to the pelvic area, treatment can cause vaginal itching, burning and dryness. Some may find sex painful. For men, radiation may affect the nerves that allow a man to have erections. If you are experiencing sexual side effects due to radiation therapy, your care team can offer ways to help.

Low blood counts. While this side effect is uncommon, radiation therapy can cause changes in your blood count levels, making it harder for your body to fight off infection and prevent bleeding. If your blood tests reveal low blood counts, your treatment may be stopped for a short period so that your blood counts can return to normal. This side effect is more likely if you’re also receiving chemo.

Secondary cancers. Receiving radiation therapy may increase your risk of developing another cancer later in life. However, the chances of this happening are small. If you’re worried about the possibility of developing a secondary cancer due to radiation exposure, be sure to speak with your care team.

Site-specific side effects of radiation therapy

In addition to the general side effects listed above, radiation therapy can cause different side effects based on the type of treatment and the targeted part of the body.


  • Difficulty swallowing
  • Shortness of breath
  • Shoulder stiffness
  • Breast or nipple soreness
  • Cough, fever or chest fullness (radiation pneumonitis)
  • Permanent lung scarring (radiation fibrosis)

Head and neck

  • Difficulty swallowing
  • Dry mouth
  • Mouth and gum sores
  • Jaw stiffness
  • Tooth decay
  • Earache
  • Nausea
  • Hair loss
  • Lymphedema
  • Changes in taste

Stomach and abdomen

  • Nausea and vomiting
  • Loss of appetite
  • Bowel cramping or pain
  • Loose stool, diarrhea or constipation
  • Difficulty controlling bladder


  • Nausea and vomiting
  • Loose stool, diarrhea or constipation
  • Loss of libido or ability to enjoy sex
  • Difficulty controlling bladder
  • Fertility issues

Radiation recall

Radiation recall is an acute inflammatory reaction that can occur when certain anticancer drugs are given after radiation therapy. It can occur weeks, months or years after radiation therapy has ended. It usually affects the part of the body that received radiation, especially the skin. On the skin, radiation recall may look like a severe sunburn and may cause the skin to blister, peel and swell. It may also be tender.

Coping with side effects of radiation therapy

While the side effects of radiation therapy can be difficult to manage, there are things you can do to minimize them and improve your quality of life. Here are some tips to help you cope:

  • Get enough sleep. Exhaustion can make it difficult to handle the stress of going through cancer treatment. Getting enough sleep can help build up your strength during the treatment process. Your doctor can help you cope with insomnia and fatigue.
  • Practice healthy skincare. Your radiation oncology nurse will give you tips for taking care of skin that has been exposed to radiation. It’s important to be gentle with your skin and use mild soaps, protect your skin from the sun and avoid rubbing or scratching the treated area.
  • Eat a balanced diet. Because many cancer patients experience nausea and vomiting during treatment, it can be hard to make sure you’re getting all the nutrients you need. Eating a balanced diet is crucial to keeping your body strong, so if you’re having trouble with your appetite, eating small, frequent meals throughout the day can be helpful. High-calorie meal replacement drinks may also be a good option.
  • Stay hydrated. Certain side effects, including vomiting and diarrhea, may put you at higher risk for dehydration. Getting enough fluids is important for maintaining energy levels and helping your body heal. If water isn’t appealing to you, consider adding a splash of fruit juice or sucking on ice chips.
  • Exercise regularly. Engaging in physical activity during and after treatment can boost your energy levels and help you manage stress. Even a short walk or some light yoga can be beneficial to your health, but be careful not to push yourself too hard.
  • Get the emotional support you need. Many cancer patients feel depressed, angry or helpless during treatment. Whether you and your loved ones are struggling to bear the emotional burden of cancer treatment, or you’d like to speak to a psychologist or chaplain, we’re here to provide support. The Siteman Psychology Service and Spiritual Care and Interpreter Services are available to patients and their loved ones. Some of their services include providing education and counseling, teaching coping skills and connecting patients to support groups.