Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Cancer Health Center

Font Size

Oral Complications of Chemotherapy and Head/Neck Radiation (PDQ®): Supportive care - Health Professional Information [NCI] - Late Complications of Head and Neck Radiation



Trismus has been associated with significant morbidity post-radiation therapy, with significant health implications, including reduced nutrition due to impaired mastication, difficulty in speaking, and compromised oral hygiene.[30] Limitations in jaw opening have been reported in 6% to 86% of patients who received radiation to the temporomandibular joint and/or masseter/pterygoid muscles, with frequency and severity that are somewhat unpredictable.[31]

The loss of function and range of mandibular motion from radiation therapy appears to be related to fibrosis in and damage to the muscles of mastication. Studies have demonstrated that an abnormal proliferation of fibroblasts is an important initial event in these reactions. Additionally, there may be scar tissue from radiation therapy or surgery, nerve damage, or a combination of these factors. Regardless of the immediate cause, mandibular hypomobility will ultimately result in degeneration of both muscle and temporomandibular joint.

Radiation therapy involving the temporomandibular joint, the pterygoid muscles, or the masseter muscle is most likely to result in trismus.[30] Tumors related to this type of radiation can appear in the following locations:

  • Nasopharynx.
  • Oral cavity.
  • Oropharynx.
  • Base of tongue.
  • Salivary gland.
  • Maxilla or mandible.

The prevalence of trismus increases with increasing doses of radiation, and levels in excess of 60 Gy are more likely to cause trismus.[5] Patients who have been previously irradiated and who are being treated for a recurrence appear to be at higher risk of trismus than those who are receiving their first treatment.[32,33] This suggests that the effects of radiation are cumulative, even over many years. Radiation-induced trismus may begin toward the end of radiation therapy or at any time during the subsequent 24 months. Limitations in opening the mouth often increase slowly over several weeks or months. The condition may worsen over time or remain the same, or the symptoms may reduce over time, even in the absence of treatment.

Limited mouth opening frequently results in reduced nutritional status. These patients may experience significant weight loss and nutritional deficits.[34] It is generally accepted that weight loss of more than 10% of initial body weight is considered significant. This is of particular importance at a time when the patient is recovering from surgery, chemotherapy, and/or radiation therapy. Additionally, it lowers the ability for social eating and thereby increases the risk of social isolation and decrease in quality of life in patients with HNC.

Next Article:

Today on WebMD

Colorectal cancer cells
New! I AM Not Cancer Facebook Group
Lung cancer xray
See it in pictures, plus read the facts.
sauteed cherry tomatoes
Fight cancer one plate at a time.
Ovarian cancer illustration
Real Cancer Perspectives
Jennifer Goodman Linn self-portrait
what is your cancer risk
colorectal cancer treatment advances
breast cancer overview slideshow
prostate cancer overview
lung cancer overview slideshow
ovarian cancer overview slideshow
Actor Michael Douglas