Radiation therapy to the breast can cause side effects. These side effects begin within a few weeks of starting treatment and improve after treatment ends. Before you begin radiation therapy, talk with your health care team about possible side effects and how to manage them.

Some short-term side effects of radiation therapy include:

• Fatigue
• Pain, and
• Skin changes like redness, swelling and irritation

Fatigue is a common side effect during treatment and can last for several weeks afterwards. You may feel tired all the time and resting may not help. Studies have shown that regular exercise like walking 20 minutes a day can help decrease fatigue. A good night’s sleep is also important.

During treatment and just after, the treated breast may feel sore or look red and irritated. Mild pain relievers such as ibuprofen or acetaminophen can ease breast tenderness. Sometimes the skin may peel, like a sunburn. If this happens, your health care team may suggest special creams that can help ease any discomfort.

Sometimes, side effects from radiation therapy can appear months or years later. These are called long-term side effects. These may include firmness, or change in size of the breast, or slight darkening of the skin where the area was treated. These changes may be permanent.

Lymphedema is another long-term side effect of radiation therapy. It’s a condition that happens when fluid builds up and causes swelling, often in the arm, hand or other areas of the body. There’s a risk of developing lymphedema if you have radiation to the axillary lymph nodes, which are in the underarm area, or the supraclavicular lymph nodes, which are above the collarbone. The risk is greater if your treatment also includes the removal of axillary lymph nodes during surgery.

If you notice any of these side effects during and after radiation treatment, let your health care team know. They may be able to recommend things to help ease the side effects.

For more information, visit the Radiation Therapy page within the Treatment section of komen.org.