University of California San Francisco
Helen Diller Family Comprehensive Cancer Center

Radiation Therapy Side Effects

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Radiation will not make you feel sick or nauseated like chemotherapy can. The side effects are generally limited to the area of the body that is treated and usually don't begin until the second or third week of treatment. The most common side effect of radiation to the breast area is a sunburn, redness, tanning or dryness and peeling of the skin. Your skin changes will be monitored weekly. We will advise you of the creams and lotions you need to care for your skin. You may feel tenderness or experience some swelling or heaviness in the treated breast. The radiation may cause inflammation but this is only temporary. Most of the skin changes resolve within a few weeks after the treatment is over.

You may also experience fatigue. It is usually not severe. It does not start until the third or fourth week of treatment and not everyone experiences this. It usually disappears once the treatment is over. It is possible to work during treatment. Whenever possible take time to rest and relax.

Long term side effects or complications of radiation are unusual and usually are related to the area(s) of the body that are treated. Your physician will discuss the risks particular to your case. You may be concerned that radiation will cause another cancer. The risk of developing another cancer because of radiation is very low. The benefit of treatment outweighs the very small risk of another cancer. However, if you smoke it is extremely important that you quit smoking to reduce your risk of lung cancer.

Note: The information above was reproduced from the UCSF Radiation Oncology website at