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Welcome

Welcome to the Toronto General Hospital Department of Anesthesia and Pain Management's Malignant Hyperthermia website. This site is intended to provide information about the Malignant Hyperthermia Investigation Unit at Toronto General Hospital, as well as providing a tool for clinicians to learn about MH, its treatment, and current research.

What is malignant hyperthermia?

Malignant hyperthermia (MH) is an inherited muscle condition in which sustained contractions of muscles may occur in response to specific anesthetic drugs. Affected individuals are susceptible to life-threatening reactions to commonly used anesthetics. In very rare situations, MH reactions may occur without an anesthetic.

How common is MH?

While the exact number of MH susceptible (MHS) individuals is unknown, experts believe that fewer than 1 person in 10,000 may be affected. Many people with MHS are unaware of their condition, and more than 50% of MHS individuals may have had successful anesthesia before they learned they were susceptible. Often, it is only when they or a family member have had a severe or fatal reaction to anesthetic that a diagnosis is finally made.

Report a case of malignant hyperthermia

If you have witnessed an MH reaction, please let us know. Download our reporting PDF, fill it out, and fax it to MHIU at (416) 340-4960.