Side Effects of Radiation Therapy

Aprobado por la Junta Editorial de Cancer.Net, 07/2022

Radiation therapy can effectively treat many types of cancer. Like other cancer treatments, it often causes side effects.

There are some common possible side effects of radiation therapy, but side effects vary person to person. This is because side effects can depend on the type of cancer, its location, the radiation therapy dose, your general health, and other factors. It is important to talk to your health care team about any side effects you experience so they can find ways to help you.

This article describes why radiation therapy causes side effects, the types of side effects you can expect, and how to cope with side effects. Learn more about the basics of radiation therapy and what to expect during your radiation therapy appointments.

Why does radiation therapy cause side effects?

In this type of treatment, high doses of radiation therapy are used to destroy cancer cells. Side effects come from damage to healthy cells and tissues near the treatment area.

There have been major research advances in radiation therapy over recent years that have made it more precise. This has reduced this treatment's side effects compared to radiation therapy techniques used in the past.

Some people experience few or no side effects from radiation therapy. Other people experience more severe side effects. Reactions to radiation therapy often start during the second or third week of treatment. Or, they may last for several weeks after the final treatment. Some side effects may be long term. Talk with your treatment team about what you can expect.

Are there options to prevent or treat side effects caused by radiation therapy?

Yes. Your health care team can help you prevent or relieve many side effects. Preventing and treating side effects is an important part of your overall cancer treatment. This is called palliative care or supportive care.

Before treatment begins, ask what side effects are likely from the specific type of treatment you are receiving and when they may happen. During and after treatment, let your health care team know how you are feeling on a regular basis. This includes if you are experiencing a new side effect, or a problem persists or has gotten worse.

What are the common side effects of radiation therapy?

Radiation therapy is called a local treatment. This means that it only affects the specific area of the body that is targeted. For example, radiation therapy to the scalp may cause hair loss. But people who have radiation therapy to other parts of their body do not usually lose the hair on their head.

Common physical side effects of radiation therapy include:

Skin changes. Some people who receive radiation therapy experience dryness, itching, blistering, or peeling on the skin in the area being treated. Skin changes from radiation therapy usually go away a few weeks after treatment ends. If skin damage becomes a serious problem, your doctor may change your treatment plan. Lotion may help with skin changes, but be sure to check with your health care team about which cream they recommend and when to apply it. It is also best to protect affected skin from the sun. Learn more about skin-related treatment side effects.

Fatigue. Fatigue is a term used to describe feeling physical, emotional, and mental exhaustion even if you are getting enough rest and sleep. Many patients experience fatigue. Your level of fatigue may increase if you are receiving more than 1 type of treatment, such as radiation therapy combined with chemotherapy. Learn how to cope with fatigue.

Long-term side effects. Most side effects go away after treatment. But some continue, come back, or develop later. These are called long-term or late effects. One possible late effect of radiation therapy is the development of a second cancer. This is a new type of cancer that develops, sometimes due to the original cancer treatment. The risk of this late effect is low, but ask your health care team what signs of a second cancer you should watch for.

What are site-specific side effects of radiation therapy?

Some side effects depend on the type and location of where radiation therapy is directed at the body.

Head and neck. Radiation therapy aimed at a person's head or neck may cause these side effects:

Learn more about dental health during cancer treatment and managing eating challenges from head and neck treatments.

Chest. Radiation therapy aimed at the chest may cause these side effects:

  • Difficulty swallowing

  • Shortness of breath

  • Breast or nipple soreness

  • Shoulder stiffness

  • Cough, fever, and fullness of the chest, known as radiation pneumonitis. This happens between 2 weeks and 6 months after radiation therapy ends

  • Radiation fibrosis, which causes permanent lung scarring from untreated radiation pneumonitis. Your radiation oncologist will know how to lower the risk of fibrosis.

Stomach and abdomen. Radiation therapy aimed at the stomach or abdomen may cause these side effects.

These symptoms will likely go away after treatment. During treatment, your doctor can prescribe medicine to manage these side effects. Making changes to your diet may also reduce symptoms. It may be helpful to talk with an oncology dietitian.

Pelvis. Radiation therapy aimed at the pelvis may cause these side effects:

  • Loose stool or diarrhea

  • Rectal bleeding

  • Incontinence, which is when a person is not able to control their bladder

  • Bladder irritation

  • Sexual problems, which includes physical and emotional changes that affect your sex life and intimacy. Problems can include erectile dysfunction, which is the inability to get or maintain an erection of the penis, or vaginal itching, burning, dryness, and other changes.

  • Changes in menstruation, such as having your menstrual period stop, and symptoms of menopause

  • Fertility problems, which means it can affect your ability to have children in the future. Specific problems include lowered sperm counts and reduced sperm activity if there is radiation therapy to the testicles or prostate gland. If both ovaries receive radiation therapy, there may be problems with becoming pregnant.

What is radiation recall?

Radiation recall is a rash that looks like a severe sunburn. It is rare but it can happen when certain types of chemotherapy are given during or soon after external-beam radiation therapy.

The rash appears on the part of the body that received radiation therapy. Symptoms may include redness, tenderness, swelling, wet sores, and peeling skin.

Typically, these effects start within days or weeks of starting radiation therapy. But they can also appear months or years later. Doctors treat radiation recall with medications called corticosteroids. Rarely, it may be necessary to wait until the skin heals to continue with chemotherapy.

Coping with the side effects of radiation therapy

Everyone's experience with radiation therapy is different. Side effects vary from person to person, even when given the same type of treatment. Before your treatment, ask your health care team which physical side effects are possible and what to watch for. You may also experience emotional side effects. Seeking out mental health support to help with anxiety and stress is important.

Ask your health care team about ways to take care of yourself during the treatment period, including getting enough rest, eating well, and staying hydrated. Ask whether there are any restrictions on your regular exercise schedule or other physical activities. If so, talk with them about another way to get regular exercise.

Continue to talk to your health care team throughout your treatment. Tell them when side effects first appear, worsen, or continue despite treatment. That will help your health care team provide ways to help you feel better during and after treatment.

Questions to ask the health care team

Consider asking the health care team these questions if radiation therapy is a part of your recommended treatment plan:

  • What physical side effects are likely based on my specific radiation therapy treatment plan? When will they likely begin?

  • How can these side effects be prevented or managed?

  • How can I take care of the affected skin during my treatment period?

  • Who should I tell when a side effect appears or gets worse?

  • Are there specific side effects I should tell the doctor about right away?

  • Who can I talk with if I'm feeling anxious or upset about having this treatment?

  • If I'm having side effects that affect my nutrition, can you recommend an oncology dietitian?

  • What are other ways I can take care of myself during the treatment period?

  • Are there any restrictions on exercising or other physical activity during this treatment?

  • Could this treatment affect my sex life? If so, how and for how long?

  • Could this treatment affect my ability to become pregnant or have a child? If so, should I talk with a fertility specialist before cancer treatment begins?

  • What are the potential long-term effects of this type of radiation therapy?

  • If I'm worried about managing the financial costs of cancer care, who can help me?

  • Will special precautions be needed to protect my family and others from radiation exposure during my treatment period?

  • After radiation therapy is completed, what will my follow-up care plan be?

  • Why is follow-up care important for managing side effects of treatment?

Related Resources

Understanding Radiation Therapy

What to Expect When Having Radiation Therapy

Fear of Treatment-Related Side Effects

Proton Therapy

More Information

National Cancer Institute: Radiation Therapy Side Effects