Radiation Therapy Side Effects

This page is for people having radiation therapy, and the people helping them. It explains why side effects happen, which ones depend on the treated area, and when to get help.

Radiation therapy is aimed carefully at cancer, but it can still touch some healthy cells nearby. Radiation not only kills or slows the growth of cancer cells, it can also affect these nearby healthy cells — and that is what causes side effects.

Side effects happen because radiation can affect healthy cells near the cancer, not just the cancer itself.

Before treatment starts you have a planning session, called simulation. Marks or small permanent dots go on the skin, so you are positioned the same way each time. If the treatment area is the head or neck, a mold or fitted mesh mask may be made. Most external beam courses run once a day, Monday to Friday. The number of weeks depends on the cancer and the goal. NCI notes that most visits last 30 minutes to an hour. The beam itself is on for only one to five minutes. External beam radiation does not make you radioactive. You can safely be around children and pregnant people.

Many people who get radiation therapy have fatigue. Fatigue is feeling exhausted and worn out. It can happen all at once or come on slowly.

People feel fatigue in different ways. You may feel more or less fatigue than someone else who is getting the same amount of radiation therapy to the same part of the body.

NCI reports that more than 80 percent of people having chemotherapy or radiation get it. Sleep and rest do not relieve it, and it can follow very little activity. With radiation it usually rises after treatment starts. It peaks around the midpoint, then levels off until the course ends. NCI suggests choosing the activities that matter most and doing them when your energy is best. Staying active, such as walking, may help you feel better.

Beyond fatigue, the side effects you may have depend on which part of your body is treated. Here are some examples of possible side effects by area:

• Brain: fatigue, hair loss, memory or concentration problems, nausea and vomiting, skin changes, headache, and blurry vision.
• Breast: fatigue, hair loss, skin changes, swelling (edema), and tenderness.
• Chest: fatigue, hair loss, skin changes, trouble swallowing, cough, and shortness of breath.
• Head and neck: fatigue, hair loss, mouth problems, skin changes, taste changes, throat problems such as trouble swallowing, and a less active thyroid gland.
• Pelvis: diarrhea, fatigue, hair loss, nausea and vomiting, sexual and fertility problems, skin changes, and urinary and bladder problems.
• Rectum: diarrhea, fatigue, hair loss, sexual and fertility problems, skin changes, and urinary and bladder problems.
• Stomach and abdomen: diarrhea, fatigue, hair loss, nausea and vomiting, skin changes, and urinary and bladder problems.

It helps to discuss this list with your doctor or nurse and ask about the side effects you might expect.

The treated skin can turn red or darker. It can go dry, itchy, flaky or peeling. In some areas it can blister or weep. The usual advice runs like this:

• Wear loose clothing in soft fabrics.
• Use lukewarm water and mild soap.
• Do not rub or scrub.
• Keep adhesive tape off treated skin.
• Avoid heat or ice packs unless your team approves.
• Check with your team before using any skin product, including creams, powders or deodorants.

Ask whether any products should be avoided before a session. Protect treated skin from the sun with dark clothing or SPF 30 or higher sunscreen, as ACS advises.

Healthy cells that are damaged during radiation treatment usually recover within a few months after treatment is over. As they recover, many side effects get better.

But sometimes people have side effects that do not improve. And other side effects may show up months or years after radiation therapy is over.

NCI says healthy cells usually recover within a few months, so many side effects ease after treatment ends.

Side effects that show up months or years after treatment are called late effects. Whether you might have late effects, and what they might be, depends on:

• The part of your body that was treated.
• Other cancer treatments you have had.
• Genetics.
• Other factors, such as smoking.

Because late effects vary so much from person to person, it is important to ask your doctor or nurse which ones you should watch for. Keeping up with follow-up visits helps your team spot and manage any problems early.

• Call 911 or go to an emergency department if you suddenly cannot catch your breath, or your chest hurts, while your chest is being treated. Also go if you are suddenly confused or hard to wake, or if a fever comes with shaking chills and you feel very unwell.
• If you are also having chemotherapy, call your care team right away, day or night, if your temperature reaches 100.4°F (38°C) or higher. CDC says a fever during chemotherapy is a medical emergency and to call your doctor right away, even in the middle of the night. If you cannot reach them quickly, go to an emergency department. Chills, a sore throat, mouth sores, burning when you urinate, or any other sign of infection also mean call right away. A normal temperature is not permission to wait. See CDC on fever during chemotherapy.
• Call your care team the same day if your temperature reaches 100.4°F (38°C) or higher and you are not having chemotherapy, or the treated skin blisters, weeps, or breaks open. Infection during cancer treatment can be life threatening.
• Call your care team the same day if swallowing hurts enough that you are eating less, or loose stools keep coming and you cannot drink enough to keep up. NCI says dehydration from diarrhea can be life-threatening, so do not wait it out.