Can You Randomly Get Lockjaw? Causes

Medically Reviewed on 1/26/2022
Can You Randomly Get Lockjaw
Lockjaw (trismus) is the inability to open the mouth or jaw fully. You can randomly get lockjaw if you have temporomandibular joint (TMJ) disorder or tetanus

Lockjaw (trismus) is the inability to open the mouth or jaw fully. You can randomly get lockjaw if you have temporomandibular joint (TMJ) disorder or tetanus.

What causes lockjaw?

Lockjaw can be caused by:

What is TMJ?

TMJ affects the jaw joint and muscles that surround it due to inflammation, causing pain or locking of the temporomandibular joints located between the lower jaw and temporal bone. 

TMJ can also cause aching or throbbing pain as well as soreness in the ear, jaw, or face. Chewing food can worsen the pain, and you may experience a clicking sound or grinding sensation.

TMJ pain usually resolves on its own or with conservative medical treatment.

What is tetanus?

Lockjaw and tetanus used to be used interchangeably because tetanus can cause rigidity of the jaw muscles. Tetanus is a bacterial infection caused by Clostridium tetani that can be prevented with the tetanus vaccine. The incubation period is typically 3-21 days, although most cases occur within 14 days. 


Tetanus is caused by bacteria called Clostridium tetani and results in the jaw being locked or frozen in a position, making it hard for the person to move or even open their mouth. This occurs when the bacterial infection interferes with the nerves or joints that are responsible for controlling the jaw.

The infection occurs through cuts or wounds contaminated with tetanus bacteria, such as rusted metal. In severe cases, lockjaw can even cause death by suffocation or choking. Other ways through which tetanus bacteria can get into the body include:

  • Superficial wounds
  • Surgical procedures
  • Animal bites
  • Dental infections
  • Fracture in which the bone is exposed
  • Chronic sores and infections
  • Intravenous drugs given under non-sterile conditions
  • Intramuscular injections (shots given in a muscle) given under non-sterile conditions


  • Generalized tetanus: Starts at the jaw and progresses down the body.
  • Localized tetanus: Causes muscle spasms close to the site of an injury and can eventually lead to generalized tetanus.
  • Cephalic tetanus: Results from a head wound and causes weakened face muscles and jaw spasms.


Signs and symptoms of lockjaw caused by tetanus include:

  • Painful muscle spasms and stiff muscles in the jaw
  • Muscle tension around the mouth, sometimes producing a persistent grin
  • Painful spasms
  • Difficulty swallowing
  • Rigid neck muscles

Progression of the infection results in chronic seizure-like spasms that last for a long time. As the disease advances, symptoms may include:


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How is lockjaw diagnosed?

There are no particular tests to diagnose lockjaw. However, your doctor may perform imaging tests or X-rays to determine the underlying cause.

These tests may reveal TMJ issues, fractures, tumors, or other conditions that may be causing lockjaw.

How is lockjaw treated?

Treating the underlying condition should resolve lockjaw. Symptoms may be helped with:

  • Medications: Medications such as muscle relaxers and nonsteroidal anti-inflammatory drugs can relax the jaw muscles and relieve pain. Depending on the severity of symptoms, medications that require infusion directly into the jaw may be prescribed.
  • Therapy: Physical therapy with electrical stimulation, deep warming, massage, and stretching may help relax the jaw muscle. Some people may also benefit from the help of a speech therapist or swallowing specialist.
  • Dietary changes: Dietary changes such as eating soft foods may help reduce discomfort or difficulty chewing and swallowing.
  • Lifestyle changes: 
    • Maintain good posture
    • Stretch your neck, shoulders, and jaw muscles regularly
    • Avoid clenching or grinding
    • Massage your face muscles especially the muscles under your cheekbone
    • Practice good oral hygiene

Chronic lockjaw can cause complications if left untreated. Being unable to open your mouth properly can lead to malnutrition, dehydration, dental problems, and even choking in severe cases. It is therefore important to seek care as soon as possible.

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Medically Reviewed on 1/26/2022
Image Source: iStock Images