Radiation Therapy Side Effects and How to Treat Them

Medically Reviewed By Teresa Hagan Thomas PHD, BA, RN
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Radiation therapy, or radiotherapy, can have significant treatment benefits. However, it may also cause varying side effects, such as fatigue and functional impairments. For some people, side effects may be milder or more manageable, whereas others may experience unpleasant or painful side effects. Side effects may also impact your quality of life and your ability to carry out daily activities.

As a result, treatment options may also vary per person. However, they can help improve the side effects of radiation therapy.

This article explains more about the side effects of radiation therapy, including why they happen and the symptoms you may experience in different body systems. It also discusses the treatment and outlook of radiation therapy side effects, as well as some frequently asked questions.

Why does radiation therapy cause side effects?

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Radiation therapy works by killing harmful cells, such as cancerous cells, or slowing their growth. However, it can also damage your healthy cells, causing adverse side effects.

The type, number, and severity of side effects you experience can depend on many factors, such as:

  • what condition you have, for example, what kind of cancer
  • where on the body the radiation therapy is directed
  • the dosage of radiation you receive
  • your overall health and other individual differences

Learn more about radiation therapy, including how it works and how to prepare.

Types of side effects

When you undergo radiation therapy, you may experience different types of side effects. Clinicians may categorize side effects into the following groups:

  • Early or acute side effects: Early side effects first occur during or very soon after treatment. They are usually mild and treatable. They also tend to be short-term, going away a few weeks after treatment ends. Early side effects typically affect the skin and other soft tissues.
  • Consequential side effects: Consequential side effects can occur if early side effects do not receive necessary care and go on to cause more lasting damage. Examples include lesions to the skin.
  • Late side effects: These can take months or years to develop. Developing late side effects is rare, and can depend on where you were treated and the dosage you received. Although they can affect any tissue that has received radiation, they usually involve organs and structures such as the muscles, liver, or heart.

Treatment plans can help avoid severe long-term side effects.

Common general side effects

Some side effects are common across many types and locations of radiation therapy. These general side effects can include:

  • fatigue
  • nausea and vomiting
  • hair thinning or loss
  • low blood count levels
  • skin and scalp changes, such as:

In addition, you may also experience more local or specific side effects, depending on the area where you receive radiation therapy treatment.

Below are some of these effects.

Radiation therapy to the brain

Radiation therapy to the brain may lead to brain swelling, which can cause additional side effects such as:

  • headache
  • blurry vision
  • difficulty with memory, concentration, or speech
  • hearing impairments
  • seizures
  • in severe cases, impaired brain function

However, doctors will typically give you medication to prevent brain swelling. Contact your doctor if you experience any of these side effects, whether or not you are taking medication to prevent them.

Radiation therapy to the head or neck

In addition to more general side effects such as hair loss, radiation therapy to the head or neck can also cause side effects such as:

  • dry mouth
  • difficulty swallowing or jaw stiffness
  • changes to taste
  • soreness, or open sores in the mouth or throat
  • less active thyroid gland
  • tooth decay

Radiation therapy to the breast

If you receive radiation therapy to the breast, you may also experience symptoms such as:

Radiation therapy may also cause long-term changes in the breast, including:

  • pores becoming larger or more noticeable
  • increased or decreased sensitivity
  • skin feeling thicker
  • larger or smaller breast size

New changes should not appear after about a year following treatment. If you do notice new or worsening symptoms, contact your doctor as soon as possible.

Read more about how to monitor the breasts for changes.

Undergoing radiation therapy to the breast may also cause side effects that can involve other organs or structures. These side effects can include:

  • rib bone weakening or fractures
  • heart complications, such as irregular heartbeat or hardening of the arteries
  • lung damage
  • damage to the nerves in the shoulder or arm causing pain, numbness, or weakness

Radiation therapy to the chest

Radiation therapy to the chest may additionally cause the following side effects:

Like radiation therapy to the breast, radiation to the chest can also affect the heart and lungs. This can cause effects such as heart complications or radiation pneumonitis, the inflammation of the lungs.

Radiation therapy to the abdomen

If you are getting radiation to your stomach or abdomen, you may experience additional side effects such as:

Eating certain foods or avoiding trigger foods may help to avoid or alleviate some of these side effects. Contact your doctor or a licensed dietician for more advice on what dietary habits may be beneficial to you.

Radiation therapy to the pelvis or rectum

Radiation therapy to the pelvis or rectum may cause some of the following side effects:

  • diarrhea
  • nausea and vomiting
  • sexual problems
  • fertility problems or changes, such as infertility or early menopause
  • urinary and bladder problems, such as:
    • pain or burning during urination, or difficulty urinating
    • blood in the urine
    • an urge to urinate frequently
    • incontinence
    • fistulas
    • cystitis

Secondary cancer

Radiation therapy can increase your risk of developing a new case of cancer in the years following treatment.

However, the probability of this happening is small. Additionally, the National Health Service suggests that the benefits of receiving radiation therapy outweigh the risk of developing secondary cancer.

Additionally, a 2018 review suggests that people who receive radiation therapy may be at higher risk of secondary cancer due to other factors rather than radiation. These factors may include lifestyle and genetic differences.

When to seek medical help

If you experience side effects during or after radiation therapy, contact your doctor or specialist for further advice. You may benefit from treatment support even if you find some side effects to be relatively manageable. Additionally, some side effects may require medical care or revision.

Consulting your doctor is also important as some treatments will be more effective when used early. Some of these side effects may also require care from specialists, such as dieticians or physical therapists.

Contact your doctor as soon as possible if you experience one or more of the following circumstances after receiving radiation therapy:

  • You experience new or worsening side effects.
  • You experience side effects that you believe are severe or that are impacting your daily life or well-being.
  • You experience side effects despite taking preventative treatment.
  • Your side effects do not improve, or improve and then return, after taking treatment for them.
  • You have any concerns about the effects of radiation therapy.

How to reduce side effects of radiation therapy

Additional methods to alleviate radiation therapy side effects include:

  • getting as much rest as possible
  • avoiding scratching or wearing tight, rough, or stiff clothing over irritated skin
  • protecting the skin from the sun by using a broad spectrum SPF of at least 30 and covering it with breathable clothing
  • only washing using warm (not hot) water and asking for advice before shaving over affected skin
  • caring for any mouth symptoms by:
    • avoiding hot, rough, and spicy foods
    • avoiding added sugar, tobacco, and alcohol
    • staying hydrated
  • inquiring with your medical team or cancer organizations about available resources and support groups
  • considering counseling or therapy to help support you through the emotional impacts of treatment
  • asking your medical team what medication and complementary treatments may be beneficial and safe for you, such as physical therapy for stiffness

The American Cancer Society (ACS) also provides an online directory of support programs and services.

Learn more about treating nausea and bowel problems.

Medication options

Prescription and over-the-counter (OTC) medications may help prevent or reduce radiation therapy side effects. Medications can include:

  • anti-nausea medications
  • pain relief medications
  • radioprotective drugs, which protect healthy tissues in the treatment area

According to a 2020 review, only two drugs are currently approved by the Food and Drug Administration (FDA) for radioprotective uses. These drugs include palifermin and amifostine.

However, radioprotective drugs are only effective for certain types of radiation treatment in certain parts of the body.

Other drugs that the FDA has approved for different uses and conditions may also be beneficial. However, research is currently ongoing to secure approval and review the safety and efficacy of these drugs specifically for radiation therapy.

Contact your medical team for more personal advice on what medications may benefit you.


Some side effects of radiation therapy are acute, which means they do not last for a long time after treatment has ended.

Other side effects can be severe, long-term, or even permanent. In such cases, your doctor or medical team can provide treatment to either improve symptoms or deal with their effects more comfortably. Additionally, tailored treatment may help to prevent side effects from occurring in the first place.

For a more individualized outlook on what to expect from your treatment, contact your doctor.


Teresa Hagan Thomas, Ph.D., B.A., R.N., has reviewed the following frequently asked questions.

How long does it take to recover from radiation therapy?

Recovery time from radiation therapy will depend on many different factors, including:

  • the type of radiation therapy you are receiving
  • the location of the therapy
  • your overall health

Talk with your medical team for individual advice on what to expect.

How soon after radiation do side effects start?

Radiation therapy side effects can start during or soon after therapy.

They can also develop for the first time in the months or years after finishing radiation therapy.

Is radiation therapy painful?

Radiation therapy itself is painless. However, it can cause side effects that may be painful, such as sores in the mouth.

Medical treatments and at-home care methods may help ease this pain and other symptoms.


Radiation therapy can have many benefits, but it can also lead to side effects. Examples of more general side effects include fatigue, skin changes, and nausea.

The type, severity, and location of side effects can also vary. These depend on the condition the therapy is treating and where on the body the therapy is targeted. Side effects may develop during treatment or up to several years afterward.

Contact your doctor for any new or worsening side effects, or if you have any questions or concerns about your treatment and outlook.

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Medical Reviewer: Teresa Hagan Thomas PHD, BA, RN
Last Review Date: 2022 Nov 29
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