Trismus causes painful spasms in the muscles that surround your jaw joints (temporomandibular joints). Several conditions and issues may cause trismus. It may be a side effect of head and neck cancer treatment or happen after dental surgery. Some infections or being hit in your jaw may cause trismus. Healthcare providers treat trismus with medication and physical therapy.


What is trismus?

When your jaw muscles become so tight that you can’t open your mouth, you may have a condition known as trismus. Trismus refers to muscle spasms in your temporomandibular joint. Head and neck cancer treatment is the most common reason why people develop trismus. Healthcare providers treat trismus with medication and physical therapy.

How does trismus affect my body?

Normally, your mouth opening measures 40 to 60 millimeters. (Depending on the size of your hand and fingers, that equals the width of two or three fingers held together.) If you have trismus, you may not be able to open your mouth wider than 20 to 35 millimeters. This may keep you from eating or speaking. Most trismus symptoms go away in a few weeks. Some people with chronic or long-lasting trismus may develop depression.

Who’s affected by trismus?

Many people can develop trismus, but the condition typically affects the following groups:

  • Young adults age 18 to 25 who’ve had dental surgery to remove their lower wisdom teeth. These are the last molars on each side of your jaws. Wisdom teeth removal may cause trismus because people often have their jaws held wide open during surgery.
  • People with head and neck cancer. Research shows more than 40% of people who had radiation treatment for head and neck cancer develop trismus.
  • People with temporomandibular disorder (TMD). Trismus is a common TMD symptom.
What’s the difference between trismus and tetanus (lockjaw)?

The conditions share several symptoms. Like trismus, tetanus makes it hard for you to open your mouth and can be very painful. The difference is trismus happens because something affected your jaw, like cancer treatment or having your wisdom teeth removed. Tetanus (lockjaw) is a bacterial infection that may cause muscle spasms throughout your body.


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Symptoms and Causes

What are trismus symptoms?

The most common symptom is not being able to open your mouth as wide as usual. Other symptoms include:

  • Your jaw muscles feel tight, as if you have muscle cramps in your jaw.
  • Your jaw hurts when you’re not talking, eating or trying to move it.
  • It hurts to chew solid food.
  • It hurts when you yawn.

What causes trismus?

Trismus is linked to a long list of conditions and medical issues. The most common causes are TMD, reaction to head and neck cancer treatment or after wisdom teeth removal. Other causes include:

  • Inflammatory conditions: You may develop trismus if you have rheumatoid arthritis, osteoarthritis and scleroderma. These conditions affect your temporomandibular joint and may cause trismus.
  • Infections: Diseases like mumps and tonsillitis can trigger trismus. You may develop trismus if you have infections that affect your teeth, neck or parotid (salivary) gland.
  • Trauma: You may develop trismus if your jaw is hit or injured.
  • Peritonsillar abscess (PTA):Some people with tonsillitis develop peritonsillar abscesses — pus-filled pockets that form near your tonsils. People with PTA may develop trismus.


Diagnosis and Tests

How do healthcare providers diagnose trismus?

Healthcare providers diagnose trismus by asking about your symptoms and examining your jaw, neck and temporomandibular joint.

What tests do healthcare providers do to diagnose this condition?

Healthcare providers may do imaging tests, including computed tomography (CT) scans or magnetic resonance imaging (MRI) scans.

Management and Treatment

How do healthcare providers treat trismus?

Healthcare providers start by treating any underlying cause. For example, if you can’t open your mouth because you have an infected (abscessed) tooth, your healthcare provider may give you antibiotics or remove the infected tooth. Other possible treatments are:

  • Muscle relaxants: These are prescription medications that ease muscle spasms.
  • Physical therapy: Healthcare providers may recommend exercises or physical therapy that stretch tight jaw muscles.

I have trismus. What can I do to help myself?

  • Rest your aching jaws: Everyday habits like biting your fingernails and chewing gum puts stress on your tight jaw muscles.
  • Avoid solid foods: Substitute hard-to-chew food for soft foods or liquid meals.
  • Try homemade heat therapy: Wrap a moist hot towel around your jaw and neck and leave it for 15 to 20 minutes once an hour. The moist heat will help your muscles relax and possibly reduce muscle spasms.


How soon will I feel better?

Depending on the situation, including treatment for underlying causes, most people feel better within a few weeks.


Can I avoid developing trismus?

Trismus typically affects people who’ve had treatment for head and neck cancer. Medical researchers are studying ways to ease post-treatment trismus.

Outlook / Prognosis

What can I expect if I have trismus?

Your prognosis, or expected outcome, depends on the condition’s cause. People who have trismus after cancer treatment may have symptoms for a long time. They may need long-term physical therapy.

A note from Cleveland Clinic

Most people develop trismus after treatment for head and neck cancer. Overall, jaw spasms may seem like a minor issue compared with cancer and cancer treatment side effects. But left untreated, trismus can affect people’s ability to eat and regain strength after treatment. It can affect their ability to communicate, making them feel frustrated or isolated. If cancer treatment makes it hard for you to open your mouth, let your healthcare provider know. They’ll recommend treatment to ease your symptoms.

Medically Reviewed

Last reviewed on 08/29/2022.

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