Ear, Nose & Throat ENT Disorders What Is Lockjaw? By Kristin Hayes, RN facebook twitter Kristin Hayes, RN, is a registered nurse specializing in ear, nose, and throat disorders for both adults and children. Learn about our editorial process Kristin Hayes, RN Medically reviewed by Medically reviewed by John Carew, MD on June 01, 2020 twitter linkedin John Carew, MD, is board-certified in otolaryngology-head and neck surgery. He is an adjunct assistant professor at Mount Sinai Medical Center and NYU Medical Center. Learn about our Medical Review Board John Carew, MD Updated on June 11, 2020 Print Table of Contents View All Symptoms Causes Diagnosis Treatment Lockjaw (trismus) is when the jaw muscles spasm and affect jaw movement. If you develop this condition, your jaw may be "frozen" in a certain position, and you might not be able to open your mouth wide. Lockjaw can be painful and it cause complications, such as choking. Medication side effects, cancer treatment, and tetanus are a few a the possible causes. Symptoms of Lockjaw Lockjaw affects the whole jaw and is usually equal on both sides. It can occur suddenly, reaching its peak effect over the course of a few hours. There are a number of nerves and muscles that control jaw movement. Due to their anatomical arrangement, lockjaw is typically characterized by a jaw position that is partially open. While an inability to open the mouth fully is the most common symptom of lockjaw, several others can occur as well. Within just a few hours, lockjaw is associated with: HeadachesJaw painEaraches When you can't control your mouth, your speech may be difficult for others to understand and you can have trouble swallowing. After about a day, lockjaw can affect your oral health because you can't swallow saliva. This can cause: Xerostomia (dry mouth)Mucositis (sore and inflamed mouth) Complications If you experience lockjaw for a longer than a few days, it can affect your overall health. Complications of persistent lockjaw include: Tooth decay and ulcers in your mouth due to an inability to effectively brush your teeth and flossBruxism (teeth grinding), which can cause your tooth enamel to wear away and even your teeth to crackMalnourishment due to difficulty eatingMuscle contracture: Stiffening of the muscle characterized by a change in the muscle structure, which does not respond to treatment as easily as a muscle spasm Causes A muscle spasm is a condition in which a muscle remains in its active position and cannot relax. This can occur due to an injury to the muscle, nerve, bone, tendon, or ligament. Another common cause of lock jaw is hypocalcemia. This can sometime occur during thyroid surgery. You might think of how you often get a "Charley horse" in your leg if you don't stretch before going on a run. The muscle spasm occurring with lockjaw is essentially the same thing, just in a different location and with a range of different possible causes and risk factors. Temporomandibular Joint (TMJ) Disorders Your temporomandibular joint is located at the sides of your face, below your eyes and towards your ears. This joint is where the muscles, bones, tendons, and ligaments that control your jaw meet. Temporomandibular joint disorders, often called TMJ, can develop due to arthritis, inflammatory disease, or facial trauma. TMJ commonly results in lockjaw. Because TMJ is often a chronic condition, related lockjaw can recur even after it resolves. Infections Infections in and around your mouth or jaw muscles, such as a peritonsillar abscess, can affect the movement of the jaw, resulting in lockjaw. In rare instances, your nerve or muscle can become permanently damaged due to an infection, potentially predisposing to recurrent episodes of lockjaw. Medication Some medications can affect nerve function and may predispose or cause lockjaw. Reglan (metoclopramide) and some antipsychotic medications are the most common culprits. Rarely, anesthetics can cause a rare complication called malignant hyperthermia, which can cause muscle spasms, including lockjaw. Cancer Cancer and some cancer treatments (i.e., surgery or radiation) can cause injuries to the structures that control jaw movement. If you have had head or neck cancer, or have had surgery or radiation treatment for these cancers, you have about a 30% chance of developing lockjaw. Tetanus Tetanus occurs due to a life-threatening neurotoxin that is released by Clostridium tetani, a bacterium commonly present in the environment. Tetanus toxin can cause muscle spasms, which may affect the heart muscles, chest muscles (impairing breathing), or any voluntary muscles in the body—including those of the jaw. Tetanus is a significant risk factor for lockjaw and almost always causes it. In fact, lockjaw used to be called tetanus. However, in most parts of the world, tetanus is extremely rare because immunizations and booster shots that protect against the infection are routine. Other Medical Conditions Sometimes, nerve or muscle diseases can cause muscle spasms. For example, stiff person syndrome, a rare autoimmune disorder, can cause spasms in any voluntary muscle. Diagnosis Lockjaw is diagnosed based on your medical history and a physical examination. The effects can make it difficult for you to verbally explain your symptoms to your medical team, so most people have to describe their medical history by writing it down. Physical Examination Normally, most people can open their mouth between 35 to 55 millimeters (mm) or 1.4 to 2.2 inches wide. If you have lockjaw, you may only be able to open your mouth less than 35 mm (1.4 inches)—a distance that's less than three fingers in width. Your doctor will measure how wide your mouth can open to see if you fall in or out of the normal range. If you have lockjaw, you might not be able to close your mouth all the way, and you are likely to have trouble moving your jaw. Your doctor may also detect stiffness and tightness of your jaw muscles, and your teeth may be clenched. Tests If there is a concern that you could have an injury, infection, or tumor affecting your mouth, face, or jaw, you may need to have diagnostic testing. Imaging studies, such as X-rays, computerized tomography (CT), ultrasound, or magnetic resonance imaging (MRI) can often identify lesions in and around the jaw. In some instances, a biopsy is needed so that your medical team can more closely examine a tumor. Diagnosis of Mouth or Jaw Cancer Treatment Otolaryngologists (ENTs), dentists, and oral surgeons treat lockjaw, and they may suggest medication and/or physical therapy. Additional treatments to address the underlying problem (such as an infection) are typically necessary as well. If your muscle spasm was caused by medication, then discontinuing it is typically recommended. (Never stop a medication without your doctor's OK.) Spasm Relief and Therapy Oral and injected muscle relaxants are typically helpful. Common examples of oral medications include Flexeril (cyclobenzaprine) and Skelaxin (metaxalone). Such medications may, however, cause side effects such as drowsiness. Targeted injections, including botulinum toxin or anti-inflammatory steroids, can relax the muscle, relieving the spasm. Injections require scheduling an interventional procedure, and they do not cause the systemic side effects seen with oral medications. How Botulinum Toxin Is Used to Treat Muscle Spasms In addition to medical management, you may need physical therapy and/or speech therapy. Your therapist may also suggest at-home exercises so you can improve control of your jaw muscles. When you take part in at-home therapy, is important to avoid pushing your exercises to a painful level. Treating the Underlying Problem If your lockjaw is caused by a medical problem, you will need treatment for the cause of your lockjaw. For example, infections may necessitate oral or intravenous (IV) antibiotics. TMJ may require anti-inflammatory treatment. And tumors may require radiation or surgery. If radiation therapy or surgery is the cause of your lockjaw, then physical therapy may be the most effective treatment approach. Longstanding lockjaw after radiation therapy can be very challenging to reverse. A Word From Verywell If you have experienced lockjaw, you may be at risk for developing it again, so it is important to discuss prevention with your doctor. Preventative strategies may include avoiding medications that trigger it, getting treatment for TMJ, and maintaining regular exercise of your jaw muscles. Most importantly, if you notice the symptoms acting up, you should seek medical attention promptly to avoid contractures or other complications. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. 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[Epub ahead of print] Liu S, Zhao H, Wang Y, Zhao H, Ma C.Oral Bromelain for the Control of Facial Swelling, Trismus, and Pain After Mandibular Third Molar Surgery: A Systematic Review and Meta-Analysis.J Oral Maxillofac Surg. 2019 Mar 21. pii: S0278-2391(19)30256-3. doi:10.1016/j.joms.2019.02.044. [Epub ahead of print]