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Malignant hyperthermia: the inherited reaction to some anesthetics

What malignant hyperthermia is, what triggers it, how it is inherited, and the antidote.

2 minute read3 sources, each checked word for wordLibrary checked October 18, 2026

In short

  • Malignant hyperthermia is an inherited muscle disorder triggered by inhaled anesthetic gases and the muscle relaxant succinylcholine.Review1
  • Reactions occur in 1 in 10,000 to 1 in 250,000 anesthetics. But the genetic changes may be carried by as many as 1 in 400 people.Review1
  • Dantrolene is the specific antidote and should be available wherever general anesthesia is given.Review1

How sure each claim is:E1StrongE2GoodOfficial textReviewWhat the grades mean

What is it?

Malignant hyperthermia is a drug-triggered genetic disorder of skeletal muscle. It is a hypermetabolic response to potent volatile anesthetic gases such as sevoflurane, desflurane and isoflurane, and to the muscle relaxant succinylcholine. Rarely, it is triggered by vigorous exercise or heat.Review1

The sevoflurane label warns that in susceptible people, volatile anesthetics may trigger it, causing a high oxygen demand. It also warns that fatal outcomes have been reported.Official text2

How is it inherited?

In humans it is inherited in an autosomal dominant pattern, meaning one copy of the gene change from one parent can be enough.Review1

Reactions are uncommon (1 in 10,000 to 1 in 250,000 anesthetics). But the genetic changes may be present in as many as 1 in 400 people.Review1

How is it treated?

Dantrolene is a specific antagonist and should be available wherever general anesthesia is given.Review1

The Ryanodex (dantrolene) label lists treatment of malignant hyperthermia with supportive measures, and prevention in people at high risk.Official text3

Questions you might bring to your anesthesia team

  1. Has anyone in my family had a problem with anesthesia, a high fever during surgery, or a diagnosis of malignant hyperthermia?
  2. If so, will my anesthesia avoid trigger agents?
  3. Should I or my family be referred for testing?

Every claim in this guide was written from its sources and checked against them word for word. Its clinical review by Dr. Recio, a practicing nurse anesthesiologist (CRNA), is pending. This line changes when the review is done.

Sources

Each source opens on PubMed, DailyMed or the publisher's page. Under each one are the exact words from it that this page relies on, copied word for word and checked against the original.

  1. Malignant hyperthermia: a review. Rosenberg H, Orphanet J Rare Dis, 2015. Review Expert review
    The words this page rests on
    Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that presents as a hypermetabolic response to potent volatile anesthetic gases such as halothane, sevoflurane, desflurane, isoflurane and the depolarizing muscle relaxant succinylcholine, and rarely, in humans, to stressors such as vigorous exercise and heat. The incidence of MH reactions ranges from 1:10,000 to 1: 250,000 anesthetics. However, the prevalence of the genetic abnormalities may be as great as one in 400 individuals.
    Dantrolene sodium is a specific antagonist and should be available wherever general anesthesia is administered.
    In humans the syndrome is inherited in an autosomal dominant pattern, while in pigs it is autosomal recessive.
  2. ULTANE (sevoflurane) volatile liquid for inhalation, Prescribing Information. AbbVie Inc., 2025. Official text FDA label
    The words this page rests on
    In susceptible individuals, volatile anesthetic agents, including sevoflurane, may trigger malignant hyperthermia, a skeletal muscle hypermetabolic state leading to high oxygen demand. Fatal outcomes of malignant hyperthermia have been reported.
  3. RYANODEX (dantrolene sodium) injectable suspension, Prescribing Information. Eagle Pharmaceuticals, Inc., 2024. Official text FDA label
    The words this page rests on
    RYANODEX is a skeletal muscle relaxant drug indicated for: Treatment of malignant hyperthermia in conjunction with appropriate supportive measures. (1) Prevention of malignant hyperthermia in patients at high risk.