Radiation therapy kills cancer cells, but it can also damage healthy cells, causing side effects like fatigue, nausea, and skin changes. Certain medications may help.

Radiation therapy is a common part of the treatment plan for many types of cancers. It uses targeted doses of radiation to kill cancer cells or slow their growth.

Sometimes, radiation is the only treatment you need. But in most cases, doctors combine it with other treatments like chemotherapy or surgery. Doctors use it:

  • before other treatments to shrink a tumor
  • after other treatments to destroy any remaining cancer cells
  • to reduce symptoms if the cancer is not curable

Here’s more on what kinds of side effects to expect and some advice on how to manage them.

Early vs. late side effects

Early side effects typically occur within weeks of starting radiation treatment. Many of these side effects improve once treatment is finished. Early side effects may include fatigue, nausea, skin changes, and hair loss.

Late side effects may not appear until after your radiation treatment ends. For example, if you have radiation to your chest area, it’s possible to develop lung or heart disease months or years later. It’s important to continue to follow up with your cancer care team to monitor for long-term effects.

Everyone will respond differently to radiation therapy. Side effects will depend on the location of the radiation treatment. Still, some side effects are common, regardless of where you received treatment.

Radiation affects your cells’ ability to divide. Cells that grow and divide the fastest are the most affected. This includes cancer cells, but can also include:

  • skin cells
  • hair cells
  • blood cells
  • cells in the digestive tract

Here are some of the most common side effects of radiation.

Fatigue is a very common effect of radiation. Your body needs a lot of extra energy to heal and recover from treatment. It’s not typical fatigue that extra sleep will fix. This kind of fatigue can make it very hard to get through the day.

Fatigue will be worse if radiation has also caused anemia. Anemia can develop if radiation kills too many red blood cells, which carry oxygen around the body. Low levels of red blood cells are a major cause of fatigue in people with cancer.

Tips for managing fatigue

  • Rest when you can.
  • Ask for help with household tasks.
  • Prioritize your energy.
  • Take any iron supplements for anemia as directed by your doctor.
  • Consider gentle movement as a way to boost your energy levels.
  • Practice relaxation strategies, such as meditation, yoga, or massage.

Skin cells are prone to damage from radiation because they divide so quickly. Radiation can affect your skin at the site where you receive treatment.

Your skin may become red and itchy or appear darker. These changes often happen within a few weeks of starting radiation. Some people may get permanent scarring.

Tips for skin care during radiation

  • Use gentle soaps and skin care products to prevent further irritation.
  • Wear long sleeves and pants and use sunscreen and SPF lip balm to avoid further sun damage.
  • Use caution with things that may cause more damage, such as heating pads or shaving.
  • Keep nails trimmed to avoid accidental damage from scratching your skin.

Talk with your radiation care team before starting to get advice on any specific lotions or soaps. Some types can worsen skin damage if you apply them before your daily treatment.

Hair thinning or loss can happen in the area treated with radiation. Greater amounts of radiation will usually cause greater amounts of hair loss.

Hair often starts to grow back within 3 to 6 months after radiation finishes. When it grows back, its texture or thickness may have changed.

If you’ve lost hair on your head, your scalp may be sensitive. Consider wearing a hat or head covering to protect it. If you decide to wear a wig, make sure it fits well and does not cause further irritation.

It’s common to notice changes in your appetite during radiation. There are many reasons for this. Fatigue, changes in taste and smell, dry mouth, or nausea can all make it hard to eat.

This side effect can start early in treatment. For many people, it gets better once treatment finishes.

Tips for navigating appetite changes

  • Keep simple, ready-to-eat snacks around.
  • Set a timer to remind you to eat every few hours.
  • Sip on nutritional supplement drinks or smoothies.
  • If you have a metallic taste in your mouth, use bamboo or plastic utensils to eat instead of metal utensils.
  • Rinse your mouth several times a day to help with a dry mouth or an unpleasant taste. Avoid alcohol-based mouthwashes as they can be irritating and worsen your dry mouth.
  • Explore whether moving around helps improve your appetite.
  • Try bland, soft foods if your mouth is sore.
  • Choose cold foods without a smell if you’re nauseated.

Many short-term side effects of radiation therapy will resolve within weeks or months of finishing therapy. But some effects can be long term.

Everyone experiences the side effects of radiation therapy a bit differently. It will depend on the:

  • type of radiation
  • amount of radiation
  • type of cells affected

Skin cells, hair cells, and many cells in your digestive system are sensitive to radiation. They damage easily but grow quickly, and the side effects improve as new cells grow back.

Sometimes, cells are not able to repair themselves, resulting in long-term side effects.

Heart damage from radiation to the chest area may show up 10 to 30 years after radiation treatment ends.

Can radiation therapy increase your risk of other cancers?

According to an older 2018 research article, people who have had radiation therapy have a slightly higher risk of developing another cancer. But the benefit of using radiation to treat cancer usually outweighs the future risk.

Long-term follow-up is important for anyone who has had cancer. This provides a chance to catch any changes in your health early. If a second cancer does develop, there are more treatment options in the early stages.

There’s ongoing research to see whether medications can reduce damage to the salivary glands. This is a common issue for people getting radiation for head and neck cancers. The dry mouth and swallowing challenges from radiation damage are often long lasting.

A doctor may recommend amifostine, but research is split on whether it’s helpful. Its use also has several side effects.

Other medications used to manage radiation side effects may include:

  • antiemetics for nausea and vomiting
  • medications to manage diarrhea
  • steroid medications to reduce inflammation
  • topical agents, including for the treatment of mouth sores
  • medications to manage pain

There’s a lot to learn about cancer and radiation treatment. Your doctor and cancer care team are great resources.

Here are several common questions you may have about radiation therapy.

The timing of side effects can vary a lot. Some will start within days or weeks of starting therapy. Others don’t happen until months or years after treatment ends.

Many of the side effects of chemotherapy and radiation are similar. Both treatments work to kill cancer cells. Both also damage healthy cells in the process.

Radiation can be a more targeted therapy. In some cases, there are fewer side effects than chemotherapy.

The type and severity of side effects from either treatment will also depend on the:

  • type of cancer
  • type and doses of chemotherapy or radiation used
  • duration of treatment
  • area of the body undergoing treatment

For many people, both radiation and chemotherapy may be part of the treatment plan.

External beam radiotherapy targets the radiation at the tumor to kill cancer cells. There’s no lingering radioactivity. You don’t need to worry about being radioactive at any time during or after treatment.

If you have internal radiation therapy (brachytherapy), you may need to be cautious. Brachytherapy involves placing a contained dose of radiation near the tumor. While it’s active in your body, you may give off a bit of radiation.

While it’s active, you may need to limit contact with all people. You may just need to avoid pregnant people and young children. This will depend on the radiation dose.

Yes. Both external beam radiotherapy and brachytherapy are safe for older adults. Radiation can be an important part of improving the quality of life for older adults with cancer.

Sometimes the cancer is not curable, or surgery is not an option. Radiation can help shrink the tumor to reduce symptoms.

Radiation therapy is a common treatment for many types of cancer. It targets cancer cells to damage and kill them. Doctors may use radiation to eliminate cancer or shrink a tumor to reduce its effects.

Side effects from radiation happen when radiation damages otherwise healthy cells. Common side effects of any type of radiation include fatigue, appetite changes, hair loss, and skin changes. Some side effects are more specific to the site undergoing treatment.

Side effects may be short-term and improve once treatment ends. Other side effects are more permanent. There is also the potential for effects to occur months or years after treatment ends.