Canadian Cancer Society logo
You are here: 

Radiation to the head and neck

There is always the potential for some side effects to occur when radiation therapy is given to the head and neck area. Radiation therapy can irritate the mucous membranes lining the mouth, throat and upper part of the esophagus. It can also affect other structures in the treatment area. Most side effects usually begin 2–3 weeks after treatment begins. Many go away once treatment is over, but a few may continue or occur long after radiation treatment.

Side effects vary depending on the area of the head and neck treated with radiation therapy.

Skin reactions

The scalp or skin of the face or neck in the treatment area may become dry, itchy, red and tender because of radiation therapy. These side effects usually occur about 2–3 weeks after treatment starts and go away a few weeks after treatment ends. The scalp, face and neck should be protected from the sun and cold by wearing a hat, turban or scarf. The radiation therapy team will give instructions for skin care and sun protection, including when it is okay to use sunscreen.

Sore mouth

A sore mouth (also called stomatitis or oral mucositis) occurs because rapidly growing cells lining the mouth are sensitive to the effects of radiation. Painful sores can occur in the mouth and on the tongue, gums or lips. The mucous membranes that line the mouth, throat and esophagus can become inflamed.

A sore mouth occurs about 2–3 weeks after radiation therapy starts. It often improves a few weeks after treatment is finished.

Thorough, regular mouth care can help prevent a sore mouth and reduce infection. The radiation therapy team will give instructions about how often to clean and rinse the mouth and what to use. Pain medicines or special oral solutions may be needed to relieve pain.


People who receive radiation therapy to the head and neck can be prone to mouth or throat infections, such as yeast infection (thrush) or oral herpes (the virus that causes cold sores or fever blisters). Mouth sores and signs of infection should be reported to the radiation therapy team.

Medicines or special oral solutions may be prescribed to fight bacterial, fungal or viral infections.

Dry mouth

Dry mouth (xerostomia) happens when radiation damages the salivary glands and the amount and quality of saliva is lowered. Dry mouth occurs within the first 2–3 weeks of treatment and can become worse over time. It may take months or years for dry mouth to go away. The salivary glands may not recover completely and dry mouth can become a permanent problem.

It is important to follow the radiation therapy team’s instructions for mouth care. They may prescribe artificial saliva and can suggest other ways to cope with a dry mouth.

Changes in taste

Taste changes can occur when radiation therapy damages the salivary glands and taste buds on the tongue, which can affect the way some foods taste or smell. The taste buds are very sensitive to the effects of radiation and symptoms often occur during the first or second week of treatment. A variety of taste changes can occur because of radiation therapy.

  • Salty and bitter tastes are usually affected the most.
  • Some foods, such as meat, may start to taste bitter or metallic.

There are many ways to cope with taste changes. The radiation therapy team or a registered dietitiandietitianA healthcare professional who specializes in food and nutrition. can suggest ways to deal with taste changes.

Taste may return to normal 1–3 months after radiation treatment is finished.

Difficulty swallowing

Radiation to the head and neck can damage the salivary glands so they don’t produce enough saliva. It can also cause inflammation of the throat (pharyngitis) or esophagus (esophagitis). Not enough saliva and inflammation can lead to difficult or painful swallowing. This side effect usually starts about 2 weeks after treatment begins.

Report difficult or painful swallowing that causes problems eating to the radiation therapy team. They can make suggestions that will help. Medications, such as antacids, may be given to ease pain caused by an inflamed esophagus. Difficulty swallowing because of pharyngitis or esophagitis often goes away when treatment ends, once the inflammation decreases.

Loss of appetite

Loss of appetite (anorexia) can be caused by:

  • a buildup of waste products as cancer cells die
  • difficulty swallowing
  • nausea and vomiting
  • fatigue
  • changes in taste or smell that make foods less appetizing

Loss of appetite is a common side effect with radiation therapy to the head and neck. This side effect can lead to weight loss and malnutrition. Maintaining good nutrition during and after radiation therapy is important to help a person recover from treatment. Steps can be taken to help increase appetite, help people eat more and maintain their nutrition. Nutritional supplements may be recommended. A registered dietitian can often help people deal with loss of appetite.

Nausea and vomiting

Nausea and vomiting are not common side effects of radiation therapy to the head and neck, but they can occur. Nausea and vomiting may occur after the first or second week of radiation therapy. They can usually be managed with antinausea medication and usually go away after treatment is finished.

Thinning or loss of hair

Thinning of hair or hair loss (alopecia) only occurs within the treated area. It usually happens about 2–3 weeks into radiation therapy treatment. People may lose some or all of the hair on the scalp, depending on the dose of radiation.

Hair loss may be temporary when lower doses of radiation are used. It is important to be gentle with the hair by using a mild shampoo and a soft hairbrush, and letting hair dry naturally. Hair often regrows 3–6 months after radiation treatment is over. Hair loss is more likely to be permanent with high doses of radiation.

Earaches or difficulty hearing

Earaches or difficulty hearing can occur if the ear is in the treatment area. These problems may be caused by hardened earwax, irritation and damage to the middle or inner ear because of radiation therapy. The ear should be protected from exposure to the sun and cold.

Hearing difficulties should be reported to the radiation therapy team. Sometimes eardrops may be prescribed. These symptoms usually go away 1–2 weeks after radiation treatment has ended.

Voice changes

Changes to the voice or hoarseness may occur if the larynx (voice box) is in the radiation treatment area. These changes are caused by swelling and inflammation of the vocal cords (laryngitis).

Hoarseness can occur 2–3 weeks into treatment. Avoid straining to speak if hoarseness becomes severe. People should also avoid alcohol and tobacco. Speech therapy, including exercises and devices, may be needed to help strengthen the voice. These side effects usually go away gradually after treatment is over.

Tooth decay

Tooth decay (also called dental cavities or dental caries) is a late side effect of radiation therapy to the head and neck. Dry mouth (xerostomia) and the effect of radiation on tooth enamel can increase the chance of dental cavities developing. Saliva helps to clean the teeth and gums, so there is an increased risk of developing cavities and gum disease when less saliva is made.

A checkup with a dentist is often done before treatment is started. Good mouth care is very important to prevent problems. Sugary snacks should be avoided because sugar promotes tooth decay when there is little saliva. Fluoride treatments may be prescribed to help protect teeth from developing cavities. Regular visits to the dentist after treatment are often recommended.


Osteoradionecrosis is death of bone caused by radiation. The bone dies because of damage to the blood vessels. Osteoradionecrosis occurs more commonly in the lower jawbone (mandible). Osteoradionecrosis rarely occurs, but when it does it can lead to infection, fractures of the bone or pain. It is most often a late effect that develops after radiation therapy has ended, so people are at risk for developing osteoradionecrosis for years following radiation therapy.

Dry mouth (xerostomia) also contributes to osteoradionecrosis of the jaw bones. Good mouth and dental care can help prevent this problem. Any teeth that need to be removed are taken out before radiation treatment starts, so a dental checkup is often done before treatment begins. Daily fluoride rinses are often prescribed.

Treatment for osteoradionecrosis may include:

  • antibiotic therapy
  • surgery to remove or repair diseased bone
  • hyperbaric oxygen treatment (oxygen improves blood flow to the area and helps control infection)


Radiation therapy to the jaw can cause scarring of the chewing muscles. Scarred muscles make the jaw stiff and sometimes prevent the mouth from opening wide. This side effect is called trismus. Trismus can occur after radiation therapy is completed and can interfere with oral hygiene, fluoride treatments and dental care. Jaw exercises, such as opening and closing the mouth, can help and should be done regularly during and after radiation therapy.

Vision changes

Vision changes can occur when radiation damages the blood vessels of the eye or the optic nerve. Radiation can cause dry eyes and vision loss. It can also cause cataracts (the lens of the eye becomes cloudy). Vision changes most often occur long after radiation therapy is finished and are more likely to happen when high doses of radiation are given.

Regular eye exams can detect changes to vision or cataracts.

Thyroid problems

Radiation to the neck can cause hypothyroidism (a decrease in thyroid function). The thyroid makes hormones that help control and maintain many body functions. Symptoms of hypothyroidism include fatigue, hair loss, brittle nails, dry skin or changes in menstruation in women.

Hypothyroidism usually develops 3–4 years after treatment, but can also occur several years later.

Thyroid function is checked and daily medications (thyroid hormone replacement) may be needed to regulate the thyroid.

Radiation myelopathy

Radiation myelopathy is damage to the spinal cord caused by radiation therapy. The 2 types of radiation myelopathy are transient and late, or delayed.

Transient radiation myelopathy is characterized by Lhermitte’s sign, which is an electrical shock-like sensation in the neck, back or legs. It usually happens when the neck is bent forward. This side effect most often occurs 2–6 months after radiation therapy. It usually improves without treatment and is not linked with any long-term problems.

Late, or delayed, radiation myelopathy develops months or years after radiation therapy. It is characterized by weakness, not being able to feel temperature or loss of proprioception, which is the sense that deals with feelings of body position, posture, balance and motion. Late radiation myelopathy does not usually improve on its own and may lead to gradual paralysis.


Marie Whitehead Catch the cancer early. That’s the number one thing. It could save your life.

Read Marie's story

Celebrating cancer survivors at Relay For Life

Relay For Life illustration

For cancer survivors, the Canadian Cancer Society provides a unique opportunity to celebrate their courage in the fight against cancer. During hundreds of Relay For Life events across the country, thousands of survivors join together for the Survivors’ Victory Lap.

Learn more