The side effects you may experience will depend on the part of the body that is being treated and how much treatment you have. Side effects only affect the part of the body that is treated. Everyone reacts to radiotherapy differently and many people have hardly any side effects. The radiographers will give you lots of support and advice to care for and manage the side effects.
You will also be given written information about the side effects relevant to your treatment. Most side effects are temporary and they are rarely severe. They may start at varying times during treatment and disappear in the weeks after the end of it. Some side effects may not start until treatment is finished.
Your doctor will discuss any possible temporary or permanent side effects with you before the start of your treatment and before you sign your consent form. Extra written information may be available.
Skin problems are common with external radiation therapy because the radiation travels through the skin to reach the area being targeted for treatment. The skin in the radiated area may become red, dry or itchy. It may change color (become darker or tanned looking). Most skin reactions happen within the first 2 weeks of starting radiation therapy. They usually go away a few weeks after treatment, but some skin changes, like skin darkening or scarring, can be permanent. Some people do not experience any skin reactions with radiation therapy.
Hair loss (alopecia) or thinning of hair only happens in the area being treated with radiation therapy. How much hair loss you have and regrowth varies from person to person and depends on the dose of radiation. Hair loss can begin about 2 to 3 weeks after radiation therapy starts. Smaller doses of radiation usually result in temporary hair loss. Permanent hair loss is more common at higher doses. When hair regrows, usually about 3 to 6 months after radiation therapy is finished, the color or texture may be different and it may grow back thinner or patchy.
Loss of appetite can start within the first few weeks of radiation therapy and can continue after treatment has ended. Side effects like sore mouth, dry mouth, problems swallowing and nausea and vomiting can cause loss of appetite. Radiation therapy to the head and neck area can cause temporary changes in taste or smell, which can make foods seem less appetizing. Some people lose interest in food completely and don’t eat, even though they know they need to. Maintaining good nutrition during and after radiation therapy is important to help a person recover from treatment.
Nausea and vomiting can be a common side effect of external radiation therapy, especially if the treatment area includes the stomach and abdomen. It can also happen as a general side effect regardless of the area being treated. Radiation sickness usually goes away a few weeks after radiation therapy is finished.
Low blood cell counts happen because of radiation’s effect on blood cells made in the bone marrow. Low blood cell counts are more common if you receive chemotherapy at the same time as radiation therapy or if the treatment area includes the pelvic bones (where many blood cells are made). Low blood cell counts are usually not severe enough to cause problems. When there is a break from treatment for a few days, blood cell counts usually recover.