Lockjaw Explained

Medically Reviewed By Avi Varma, MD, MPH, AAHIVS, FAAFP

Lockjaw is a common name for the conditions tetanus and trismus. It involves the tightening of the muscles in your jaw. This article defines lockjaw. It also discusses the symptoms, causes, and treatment options associated with the complication.

What is lockjaw?

Male with his hand on his jaw, facing away
Demetr White/Stocksy United

Tetanus is commonly known as lockjaw. People refer to tetanus as lockjaw because one of the main symptoms of the infection is tightness in the muscles of the jaw.

Tetanus has become very rare in the United States, mostly due to the tetanus vaccine. It is so uncommon that there are only about 30 cases Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source of lockjaw reported each year. Almost all of those cases occur in people who have not been vaccinated against tetanus.

Tetanus can become a life threatening illness, as the tightness that often begins in the jaw can spread throughout the body. This can cause difficulty with breathing and is potentially fatal. If you have not had a tetanus vaccine or cannot remember when you last received a booster and you sustain a wound outdoors, seek medical attention and ask for a tetanus booster.

Another condition called trismus is also commonly known as lockjaw. This is the result of persistent spasms in the muscles of the jaw.

Historically, lockjaw only referred to tetanus and the symptoms it causes. However, in recent years, it has become a phrase that is used to describe any condition that restricts someone’s ability to open their mouth.

What are the symptoms of lockjaw?

Symptoms of lockjaw vary depending on the cause of it.


The symptoms of tetanus typically occur 4–21 days after infection. However, the average time for people to begin to notice symptoms is 10 days after infection.

The symptoms of tetanus include:

  • jaw cramping
  • sudden involuntary muscle spasms, especially in your stomach
  • muscle stiffness throughout your body that is typically painful
  • difficulty swallowing
  • jerking, staring, or seizures
  • headaches
  • fever and sweating
  • changes in your blood pressure and heart rate

If you are experiencing any symptoms of tetanus, contact your doctor or seek medical care right away.

Learn what you need to know about the tetanus shot.


Trismus typically develops slowly. Many people do not even know that they are developing it.

One way to know if you may have trismus is by conducting the three-finger test. This test involves placing three fingers in your mouth vertically. If all three fingers fit from top to bottom, you have typical jaw movement. If only two fingers fit, you may be developing trismus.

Symptoms of trismus include:

  • jaw stiffness
  • pain when you open or close your mouth
  • a decreased ability to open your mouth wide

What causes lockjaw?

Lockjaw typically refers to either tetanus or trismus. Each of these is the result of different causes.


Tetanus is the result of a bacterium called Clostridium tetani. This bacterium becomes an infection when it enters your body. This typically happens when the spores enter through a puncture wound, a cut, or any other type of broken skin.

Tetanus is more likely Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source to enter your body through certain types of cuts and wounds. These include:

  • wounds that might be contaminated with feces, dirt, or saliva
  • wounds that are the result of a puncture in the skin by an object such as a nail or a needle
  • burns
  • crush injuries
  • injuries that cause dead tissue

Tetanus can also get into your body through other means, though some of these are less common. They include:

  • superficial wounds
  • surgical wounds
  • dental infections
  • insect bites
  • chronic sores or infections
  • compound fractures
  • intramuscular injections
  • IV drug use


There are many conditions that can cause trismus. These include Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source but are not limited to:

There are many other reasons you may experience lockjaw. It is typically the result of any damage to the muscles or nerves that are responsible for opening and closing your mouth.

Read about TMJ pain here.

When should you contact a doctor for lockjaw?

You should contact your doctor or seek medical treatment right away if you notice any symptoms of tetanus.

You should also contact your doctor if you have any concerns about a recent wound. This is especially true if the following statements apply:

  • The wound is deep.
  • There is dirt or debris inside the wound.
  • You are not fully vaccinated against tetanus.
  • You cannot remember if you have had the tetanus vaccine.

If you are experiencing any symptoms of trismus, you should contact your doctor. Early diagnosis and treatment can prevent trismus from getting any worse.

What are the treatments for lockjaw?

If your doctor suspects that you may have tetanus, this is generally Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source a medical emergency, and you may require hospitalization. While at the hospital, treatment may include:

  • treatment with human tetanus immune globulin
  • intensive wound care
  • medications to control any muscle spasms
  • antibiotics
  • the tetanus vaccine if you have never had it or cannot remember when you last had it

If you are experiencing trismus, your doctor may want to treat the underlying cause of it. However, treatment for trismus itself includes:

  • Stretching: Your doctor may use tongue depressors stacked together and placed in your mouth to help stretch your jaw and widen the opening of your mouth.
  • Passive motion devices: Passive motion devices help open and close your mouth without any effort from you. This works the muscles that are associated with this motion.

Can jaw exercises help with lockjaw?

Speak with your doctor before attempting any exercises to help with lockjaw.

Active range-of-motion exercises

You can repeat these exercises three times per day. Remember to keep your head still while doing them.

  1. Open your mouth as widely as you can. You should feel a stretch but no pain.
  2. Hold the stretch for 10 seconds, then relax.
  3. Take a deep breath between repetitions.
  4. Repeat five times.
  5. Move your jaw to the left.
  6. Hold this for 3 seconds.
  7. Take a breath between repetitions, and repeat five times.
  8. Move your jaw to the right.
  9. Hold this for 3 seconds.
  10. Take a breath between repetitions, and repeat five times.

Passive stretching

You can repeat these exercises three times per day as well.

  1. Put on a pair of disposable gloves or wash your hands thoroughly with soap and water.
  2. Place your thumb under your top front teeth.
  3. Place your index finger from your other hand on the bottom front teeth.
  4. Open your mouth as widely as you can.
  5. Push your fingers against your teeth gently to give extra resistance.
  6. You should feel a stretch but no pain.
  7. Hold this for 5–10 seconds, then relax.
  8. Take a breath between each repetition.
  9. Repeat five times.

What are the potential complications of lockjaw?

Lockjaw can lead to complications depending on the cause of it.


Tetanus is a medical emergency and can lead to health complications. These include:

Around 1–2 in 10 cases Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source of tetanus are fatal.


Trismus can also lead to other complications. These include:


Lockjaw occurs when the muscles in your jaw become stiff and you have difficulty opening your mouth as widely as you are typically able to.

The most common conditions related to lockjaw are tetanus and trismus. Tetanus is preventable with the tetanus vaccine. Trismus is not always preventable. However, if you have a condition or receive a treatment that may lead to trismus, you can help prevent it with stretches and exercises.

Tetanus is a medical emergency. If you think you are developing it, seek immediate medical attention.

If you believe that you are experiencing trismus, contact your doctor so that they can diagnose and treat it as soon as possible.

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Medical Reviewer: Avi Varma, MD, MPH, AAHIVS, FAAFP
Last Review Date: 2022 Jun 30
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