Changes to your jaw after head and neck cancer treatment

After radiotherapy or surgery for head and neck cancer, the muscles that open and close your mouth may become stiff. This can reduce how wide you can open your mouth. Doctors call this trismus.   

You may have been given mouth exercises to do to help prevent this. If you had surgery and radiotherapy the risk of trismus is greater. Techniques such as intensity-modulated radiotherapy (IMRT) help to reduce the risk of late effects such as trismus.

After radiotherapy to the head and neck, the blood supply to the jawbone may not be as good as before.  Sometimes, this leads to tissue in the jawbone dying. This condition is called osteoradionecrosis or ORN.  Most people who have radiotherapy will never develop ORN. 

Jaw stiffness and reduced mouth opening (trismus)

Jaw stiffness can develop a few weeks or sometimes months after treatment. The amount of stiffness varies from person to person. The earlier you start jaw exercises the more successful they are. The muscles become tight, making it more difficult to open your mouth once stiffness has set in.

An easy way to check how wide your mouth can open is to try to put 3 fingers vertically between your lower and upper front teeth. If you can only manage 1 or 2 fingers, you may have trismus.

Tell your doctor if you have jaw stiffness or pain, even if it is mild. You will usually be referred to a speech and language therapist (SLT) or physiotherapist for assessment and treatment. 

Your SLT or physiotherapist will measure how wide you can open your jaw at your first appointment. They will repeat this measurement at every appointment. It will help you to see what progress you are making.

Jaw exercises

Jaw exercises can help reduce stiffness and pain. They help to stretch the tissues and strengthen the muscles in your jaw. When you do them regularly, they help to increase the amount you can open your mouth.

Your SLT, physiotherapist or restorative dental consultant will show you:

  • jaw stretches you can do
  • how long to hold each stretch for
  • how many times to repeat the stretches.

They may also give you aids to help you gently stretch the jaw muscles. Wooden spatulas are often used. You place the spatulas between your upper and lower front teeth for a certain amount of time each day. You increase the number of spatulas you put into your mouth over time. This will gradually stretch the jaw muscles.

There are also hand-operated devices such as TheraBite® or OraStretch®. You put these inside your mouth to gently stretch the jaw muscles. 

If pain in your jaw gets worse during jaw exercises, you should stop and contact your SLT or physiotherapist for advice.

Your SLT or physiotherapist may also suggest you chew sugar-free gum to keep your jaw moving.


If you are having difficulty chewing or swallowing because of a stiff jaw, softer foods can be easier to eat. Your dietitian can give you more advice. Some people may need supplement drinks to take until this improves. We have more information about eating and drinking after head and neck cancer treatment.

Dental care

It is important to continue with a regular mouth care routine while your jaw is stiff. If it is difficult to reach teeth in the back of your mouth, try a small toothbrush. Tell your dentist or hygienist if you cannot brush your teeth because of a stiff jaw. They can give you more advice.

Drugs to improve symptoms

Your doctor may prescribe different drugs such as muscle relaxants or drugs to treat nerve pain to ease any pain and spasm. Botox injections may also help improve muscle pain and spasm.

Changes to the jawbone (osteoradionecrosis)

Radiotherapy to the head and neck can sometimes affect the blood supply to the jawbone.  This might cause the tissue in the jawbone to die. If this happens it is called osteoradionecrosis or ORN. Most people who have radiotherapy will never develop ORN. But certain things can increase the risk. These include:

  • smoking
  • surgery
  • having a tooth removed
  • having a dental infection
  • having a broken filling or sharp tooth which is injuring the gum
  • badly fitting dentures, which cause an ulcer in the gum.

If tissue in the bone dies, it may cause pain, numbness or a feeling of heaviness in the jaw. You may feel an area of roughness on your gum. Sometimes there is swelling around the gum and teeth may become loose. Or some very tiny parts of the bone may become loose and can be seen in your mouth.

Always tell your GP, hospital doctor or dentist if you have any of these symptoms. Remember to let them know that you have had radiotherapy to your head and neck area. They can check your mouth and arrange for you to have treatment.

Reducing the risk of osteoradionecrosis

Here are some ways to reduce your risk of osteoradionecrosis (ORN):

  • Do not smoke, because it affects the blood supply to the bone.
  • Look after your mouth and teeth and have a dental check-up every 6 months. Having an infection or a tooth removed can increase the risk of ORN. 
  • You may need to have 1 or more teeth taken out after radiotherapy. It is important to see a specialist oral and maxillofacial surgeon or dental oral surgeon to have this done in hospital. They will plan your treatment to reduce the risk of ORN developing.
  • Wear well-fitting dentures. If they rub or are sore, do not wear them. See your dentist for advice.

How osteoradionecrosis is treated

Treatment depends on whether the osteoradionecrosis is mild or more severe. Different treatments can include:

  • antibiotics to treat the infection
  • surgery, which is sometimes used to remove the dead bone
  • an antibiotic called doxycycline
  • a drug called pentoxifylline given with vitamin E (tocopheral), although there is not enough evidence to say how effective this is
  • jaw reconstruction may be necessary in severe cases
  • hyperbaric oxygen (HBO) involves breathing in oxygen at very high concentrations to help the affected jaw tissue to heal. This has been researched for many years but doctors are still unsure about any benefits of this treatment.

About our information

  • References

    Below is a sample of the sources used in our late effects of head and neck cancer treatment information. If you would like more information about the sources we use, please contact us at

    Nilsen M L, Belsky MA et al. Late and long term treatment-related effects and survivorship for head and neck cancer patients. Current treatment options in oncology. 2020. Volume 21. Issue 12.

    Machiels J.-P, Leemans C. R. et al. Squamous cell carcinoma of the oral cavity, larynx, oropharynx and hypopharynx. EHNS-ESMO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2020. Volume 31, Issue 11, Pages 1462-1475.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Chris Alcock, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 April 2022
Next review: 01 April 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

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