Malignant hyperthermia is diagnosed based on signs and symptoms, monitoring during and immediately after anesthesia, and lab tests to identify complications.

Susceptibility testing

Testing to find out if you're at increased risk of malignant hyperthermia (susceptibility testing) may be recommended if you have risk factors. Testing may include genetic testing or a muscle biopsy test.

  • Genetic testing. The abnormal gene that makes you susceptible to malignant hyperthermia is identified using genetic testing. A sample of your blood is collected and sent to a lab for analysis. Genetic testing can reveal changes (mutations) in your genes that may make you susceptible to malignant hyperthermia.
  • Muscle biopsy (contracture test). In some cases, the doctor may recommend a muscle biopsy if you're at risk of malignant hyperthermia. During this test, a small piece of muscle tissue is surgically removed for lab analysis. In the lab, the specimen is exposed to triggering chemicals for malignant hyperthermia to determine how the muscle contracts.


If you or someone in your family has malignant hyperthermia and you need to have anesthesia, it's important to tell your doctor and anesthesiologist. Drugs that do not trigger malignant hyperthermia may be used as part of your anesthesia.

Immediate treatment of malignant hyperthermia includes:

  • Medication. A drug called dantrolene (Dantrium, Ryanodex, Revonto) is used to treat the reaction by stopping the release of calcium into the muscle. Other medications may be given to correct your body's metabolic imbalance and treat complications.
  • Oxygen. You may have oxygen through a face mask. In most cases, oxygen is given through a tube placed in the windpipe (trachea).
  • Body cooling. Ice packs, cooling blankets, a fan with cool mist and chilled intravenous (IV) fluids may be used to help reduce body temperature.
  • Extra fluids. You may also get extra fluids through an IV line.
  • Supportive care. You may need to stay in the hospital in intensive care for a day or two to monitor your temperature, blood pressure, heart rate, breathing and response to treatment. Several lab tests will be done frequently to check the extent of the muscle breakdown and kidney damage. A stay in the hospital is usually required until lab values start to return to normal.

Malignant hyperthermia usually resolves within a few days with treatment.

Follow-up care

If you've experienced malignant hyperthermia due to certain anesthesia drugs, exercising during excessive heat and humidity could trigger another reaction. Talk to your doctor about any precautions you should take.

Also, check with your doctor to see if you should have genetic testing to determine if you have an abnormal gene that puts you at risk of malignant hyperthermia. Ask if close family members should also consider genetic testing.

If you have the abnormal gene that puts you at risk of malignant hyperthermia, wear a medical alert bracelet or necklace. This lets health care providers know of your risk, especially in an emergency, when you may not be able to talk.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

April 07, 2020
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  7. Urman RD, et al. Malignant hyperthermia-susceptible adult patient and ambulatory surgery center: Society for Ambulatory Anesthesia and Ambulatory Surgical Care Committee of the American Society of Anesthesiologists position statement. Anesthesia and Analgesia. 2019; doi:10.1213/ANE.0000000000004257.
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