Radiation not only kills or slows the growth of cancer cells, but it can also affect nearby healthy cells, which can lead to certain side effects. Oftentimes, patients experience mild side effects from radiation therapy and are able to continue their normal routines. 

The side effects of radiation therapy that patients experience are most commonly related to the area that is being treated by external beam radiotherapy. For example, most people don’t experience hair loss from having radiation therapy. But radiation therapy to the scalp may cause hair loss in that area on the head. 

Common side effects of radiation therapy include:

  • Fatigue. Fatigue is feeling exhausted and worn out almost all the time. Levels of fatigue are often dependent on an individual’s treatment plan, which means you may feel more or less fatigue than someone else. Oftentimes, the fatigue patients experience is usually not very severe, and patients can often continue all or some of their normal daily activities with a reduced schedule. Many patients continue to work full time during radiation therapy.

  • Skin problems. The skin on the part of your body receiving treatment can sometimes become dry and itchy. It may also blister or peel, somewhat like a sunburn. Skin problems usually go away a few weeks after treatment. For some people, though, the treated skin will stay darker and might be more sensitive than it was before.

  • Low blood counts. Cancer treatments can cause reduced levels of white blood cells that fight infection, red blood cells (called anemia), and platelets that help you stop bleeding. This is more common among patients who are also receiving chemotherapy. Your oncologist may pause your radiation treatments if they find low blood counts, giving your body time to regenerate the necessary blood cells.

Site-Specific Side-Effects of External Radiation Therapy

In addition to skin irritation and fatigue, other radiation therapy side effects you may experience depend on the part of the body that is treated. Some examples include: 

Head and neck. Radiation therapy aimed at a person’s head or neck may cause side effects such as:

  • Hair loss
  • Mouth changes
  • Taste changes
  • Throat changes, such as trouble swallowing
  • Less active thyroid gland

Chest. Radiation therapy aimed at the chest may cause these side effects:

  • Throat changes, such as trouble swallowing
  • Cough
  • Shortness of breath

Pelvis. Radiation therapy aimed at the pelvis may cause these side effects that include:

  • Diarrhea
  • Nausea and vomiting
  • Sexual problems (varying issues for men and women)
  • Fertility problems 
  • Urinary and bladder changes

Stomach and abdomen. Radiation therapy aimed at the stomach or abdomen may cause side effects such as: 

  • Diarrhea
  • Nausea and vomiting
  • Urinary and bladder changes

Breast. Radiation therapy aimed at the breast could cause side effects that include: 

  • Hair loss (under the arm or on the breast or chest area)
  • Swelling (Edema)
  • Tenderness

Side effects usually begin by the second or third week of treatment, and they may last for several weeks after the final radiation treatment. These are known as early side effects. In rare instances, side effects can linger, come back, or even develop later. These are known as late or long-term side effects. 

Coping With Side Effects of Radiation Therapy

Many patients are concerned that radiation therapy will cause another cancer. In fact, the risk of developing a second type of cancer because of radiation therapy is very low. The benefits of this type of cancer therapy far outweigh the very small risk that the treatment could cause a later cancer. 

Your Compass Oncology radiation oncologist is the best person to advise you about the side effects you may experience. Talk with them about any side effects you are having. They can give you information about how to manage them and may prescribe medicines that can help relieve your symptoms.