Trismus, also sometimes called lockjaw, is a painful condition in which the chewing muscles of the jaw become contracted and inflamed, preventing the mouth from fully opening. The earlier you receive treatment, the better the outcome

For most people, fully opening the mouth means opening it beyond 35 millimeters (mm) wide — a little greater than the width of two fingers.

When the mouth’s opening movement is restricted, a number of problems can arise. These include feeding and swallowing problems, oral hygiene issues, and even difficulty speaking.

While trismus is not widespread in the population, it’s sometimes commonly seen in certain groups, particularly in those who:

  • have had oral surgery to remove their wisdom teeth
  • have had head and neck cancer in a region involving structures that influence mouth movement
  • have undergone surgery or radiation treatment to the head and neck

Trismus is not the same condition as tetanus, which is also sometimes called lockjaw. Tetanus is an infection caused by the bacterium Clostridium tetani.

Because there’s a vaccine for preventing tetanus, it’s a rare infection in the United States. However, when tetanus does occur, you may have muscle stiffness and spasms that are painful and could occur anywhere in the body. A notable area where this occurs is in the head and neck region, where it causes trismus.

How long does it last?

In most cases, trismus is temporary and resolves within around 2 weeks.

However, in some cases, it can take longer to resolve and may even become permanent if left untreated.

Trismus may also last longer and could be more resistant to conventional treatment in those who develop fibrous tissue due to radiation therapy.

Trismus is more commonly temporary than permanent. But the earlier you start treatment, the better the chance for a greater recovery. Some treatment options include:

  • Use of a jaw-stretching device. These devices fit between the upper and lower jaw. A physical therapist will tell you which stretches to perform and how often.
  • Medication. Your doctor may recommend or prescribe a muscle relaxant, pain reliever, or anti-inflammatory medication. Some research suggests that combining corticosteroids and nonsteroidal anti-inflammatory drugs may be effective at decreasing post-operative trismus.
  • Physical therapy. This typically involves massaging and stretching the jaw to help loosen the muscles and decrease pain.
  • Dietary changes. Following a soft food diet and avoiding hard, crunchy foods is often recommended to ease pain until symptoms improve.
  • Acupuncture. While more studies are still needed, some research suggests that acupuncture could be beneficial for muscle relaxation and pain management in disorders affecting the jaw muscle.
  • Craniosacral therapy. This gentle, hands-on form of alternative therapy has been shown to help reduce chronic pain. Craniosacral therapy is often performed by chiropractors, massage therapists, and osteopaths.

There are several exercises that can help provide relief from trismus by stretching the jaw to decrease inflammation and pain. These exercises can be repeated several times throughout the day.

Be sure to massage your jaw muscles in a circular motion for 30-40 seconds before trying these exercises to help loosen your jaw muscle.

Here are a few exercises to try:

  1. Open your mouth as wide as possible, hold for 10 seconds, and then close. Repeat 5 times.
  2. Open your mouth as wide as possible, move your jaw to the right, and then close. Repeat 5 times and then do the same exercise, moving your jaw to the left.
  3. Stretch your neck by moving your head forward and backward and then turning left and right. Bend your head and press your ear to your shoulder, holding for 20-30 seconds before repeating on the other side. Repeat 5 times on each side.

Home remedies

Together with medical intervention, there are things you can do at home to help relieve trismus and prevent it from worsening. You can try these two or three times during the day.

  • Massage. Find the areas of your jaw that are painful and, moving your fingers in a circular motion, massage the area for about 30 seconds.
  • Stretch your neck. Tuck your chin into your chest and hold for 30 seconds, then bring your head back and hold for another 30 seconds. Similarly, move your head to the left and then the right. Finally, move your head in a circular motion.
  • Avoid clenching your jaw shut or grinding your teeth together. This can worsen jaw tightness and pain.
  • Take a magnesium supplement. Magnesium is an important mineral involved in pain regulation. One 2020 study also found that taking magnesium tablets or lozenges before and after oral surgery decreased the severity of postoperative pain and trismus.
  • Try using CBD. Although more research is needed, some studies suggest that applying CBD oil topically could help relax the jaw muscles and decrease pain.
  • Limit caffeine intake. Caffeine may worsen trismus by tightening the jaw muscle. For some people, it could also cause anxiety, which may also lead to jaw clenching.
  • Heat therapy. Placing a hot, moist towel on the jaw for 15 minutes each hour can relax the muscles and promote blood flow.

Trismus can occur when there’s damage or injury to the muscles of the jaw. This can happen due to:


Examples of this include when bones of the jaw are fractured or when they’re immobilized to let a fracture heal.

Oral surgery

While trismus can arise after any oral surgery, it’s sometimes seen after the extraction of wisdom teeth, especially the lower wisdom teeth. (Wisdom teeth are the last molars on each side of the jaw.)

Trismus can occur due to the inflammation the surgery creates or the hyperextension of the jaw during the procedure. It can also happen when a needle delivering the anesthetic inadvertently damages surrounding tissue. Learn more about recovery after wisdom tooth removal.

Temporomandibular joint disorder (TMJD)

On each side of your jaw there’s a temporomandibular joint. This joint acts as a sliding hinge, connecting your jaw to your skull and allowing you to open and shut your mouth. When there’s dysfunction in the joint, it can cause trismus and pain. Joint dysfunction can happen due to:

According to research studies, up to 11.2 percent of people with TMJD report having difficulty opening their jaw.

Radiation for head and throat cancer

Tumors that interfere with the function of the jaw itself can lead to trismus. But it more commonly occurs due to radiation of cancer involving the jaw. This can cause damage and lead to the creation of scar tissue around the joint area.

The Oral Cancer Foundation states that 10 to 40 percent of those with head and neck cancer receiving radiation will develop trismus. Radiation that affects the temporomandibular joint, the pterygoid muscles, or masseter muscle (all of which play a major role in chewing) is most likely to cause trismus.

The risk of trismus also seems to be dose-related. A 2016 study noted that every 10-Gy increase in radiation (after an initial 40-Gy dose) to a pterygoid muscle ups the risk of trismus by 24 percent. Gy is a unit of measurement for radiation therapy.

A mouth that will not fully open — causing opening difficulty — is the hallmark of trismus. Other symptoms may include:

  • pain in the jaw, even without movement
  • difficulty or discomfort performing activities that involve opening the mouth wide (things like brushing your teeth or biting into an apple)
  • inability to chew or swallow certain foods
  • muscle pain
  • sensation of muscle tightness and stiffness
  • headache
  • cramping in the jaw

Your doctor will first perform a thorough medical exam, specifically looking for signs of oral cancer, bone and joint abnormalities, or any other abnormal tissue in your jaw that may lead to trismus. They’ll also:

  • measure how wide you can open your mouth
  • ask about any recent dental treatments or procedures
  • ask about any possible injuries to your jaw — for example, if you were hit in the jaw during a sporting or car accident
  • ask about any history of prior surgery or radiation therapy to your head and neck
  • order imaging studies such as a CT scan or an MRI scan to help determine whether your trismus is stemming from a problem with your joints or tissues

Although trismus often resolves on its own, it’s important to talk to your doctor if you experience symptoms like difficulty chewing or jaw spasms, stiffness, or pain.

Your doctor can help determine the cause of your symptoms and evaluate the treatment for you.

Not only can seeking treatment early provide relief from pain and discomfort caused by trismus, but it can also prevent complications, including impaired swallowing, difficulty eating or drinking, and the development of fibrous tissue in the jaw joint or surrounding muscles.

While trismus can be painful, it’s usually temporary and responds well to both medication and physical therapy.

If you’re having dental surgery or radiation or surgery for head or neck cancer, talk to your doctor about ways to reduce your risk of developing the condition.

The earlier you receive treatment, the better the outcome, so don’t hesitate to seek help if you notice any trismus symptoms.