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Risks and Potential Side Effects

What are the most common risks and potential side effects of radiation therapy?

Radiation therapy is a painless cancer treatment, though it can cause irritation and inflammation in the tissues and organs in the path of the radiation beam. Radiation therapy may damage normal cells, in addition to the cancerous cells. This damage to the normal cells may cause side effects, which will be monitored and treated by your radiation oncologist.

As each person's individual medical profile and diagnosis is different, so is his/her reaction to treatment. Side effects may be severe, mild, or absent. Be sure to discuss with your radiation oncologist any/all possible side effects of treatment before the treatment begins. These will be reviewed with you individually, and you will be asked to acknowledge these and sign a consent form before treatment is initiated. Consider some of the following potential side effects of radiation therapy:

Skin Irritation

Sometimes, radiation irritates the skin, especially if a cancer is close to the skin surface, causing it to become red, sore, and/or dry. For some people, skin irritation can become a troubling side effect. If you experience irritated skin during radiation treatment, consult your radiation oncologist or one of the radiation oncology nurses regarding how to treat the problem. Also, consider the following ways to protect your skin during treatment:


Fatigue is a common side effect for all cancer patients. After weeks of radiation therapy, most people experience fatigue. Fatigue often resolves after treatment is completed.

Scientists have not determined the exact cause of fatigue. It may result from many factors, such as stress, pain, or a loss of sleep. Experts suggest that cancer patients with fatigue save their energy by limiting their activities. Ask friends and family to help you with certain tasks, such as grocery shopping. Try to rest as much as possible. Also, including some light exercises, such as walking, into your daily routine may help you build energy.

Hair Loss (alopecia)

Hair loss may occur, but should be limited to the area being treated with radiation. For example, if you have radiation to your head you may lose hair on your scalp. However, if you are receiving radiation to your lung, you will not lose hair on your head. Hair usually grows back after treatment is finished.

If you experience hair loss on your scalp following treatment for a head or neck cancer, you may consider wearing a wig. Other people choose to wear a hat or scarf. Or you may decide that none of these options are right for you. If you choose to wear something on your head, make sure it is comfortable and does not irritate your skin.

Blood Changes

White blood cells and platelets can be affected by radiation therapy if the radiation fields include large areas of bone marrow or if you have been treated previously with chemotherapy. Your radiation oncologist will monitor blood counts during treatment to detect any problems, and he or she may choose to adjust your treatment if your blood cell counts decrease. Since blood cells fight infections and prevent bleeding, treatment may even stop for a while until the blood counts increase.

Oral Health

Radiation treatment to the head and neck area can cause dry mouth, difficulty in swallowing, cavities, gum destruction, sores in the mouth, redness and irritation, altered taste and smell sensations, and other side effects. It is important to take good care of your mouth, teeth, and throat during radiation therapy. Seeing a dentist before you start your radiation treatments can help prevent problems.

If you experience oral health problems during radiation treatment to the head or neck, talk to your radiation oncologist, radiation oncology nurse, or dentist about what you can do. Consider the following approaches to reduce your risk of side effects:

Diarrhea, Nausea, and Vomiting

Radiation therapy to the abdomen may cause these side effects. Some patients experience nausea or an upset stomach a few hours after radiation treatment to the abdomen. Some patients find it helpful to eat a light meal a few hours prior to their treatment, while others prefer not to eat before their radiation treatment. You will need to work out a dietary plan that works best for you. Nausea may be most common during the first few days of treatment and taper down subsequently. Vomiting is uncommon and may be controlled with medications prescribed by your radiation oncologist. Diarrhea may also occur after a few weeks of radiation therapy to the abdomen or pelvis. Nausea, vomiting, and diarrhea are usually temporary side effects. You will likely not experience these side effects once your radiation treatments to the abdomen have been completed.

It is very important to maintain proper nutrition before, during, and after your radiation treatments. The main goal is to prevent weight loss.

If you have nausea and vomiting, choose foods that are easy to chew, swallow, and digest, such as the following:

With nausea and vomiting, try to avoid the following types of foods:

With nausea and vomiting, consider the following:

If you have diarrhea, consider foods such as the following:

With diarrhea, try to avoid the following types of foods:

Some people need to avoid milk and dairy products when they have diarrhea. This is because they may not tolerate the lactose contained in these products.

Difficulty Eating

Eating may be difficult during treatment. Radiation treatment can interfere with your body's ability to absorb and digest food. It is also normal to lose weight during radiation therapy, but eating a balanced diet is important.

Talk to your radiation oncologist or a dietitian regarding what you should eat if you experience problems such as a loss of appetite. Patients who eat well usually cope better with treatment, both mentally and physically.

The following suggestions from the National Cancer Institute (NCI) can help if you have difficulty eating or loss of appetite even when you are feeling well with cancer:

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