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Malignant hyperthermia

Last reviewed: 11 Sep 2025
Last updated: 08 Oct 2025

Summary

Definition

History and exam

Key diagnostic factors

  • exposure to potent inhalation anesthetic and/or succinylcholine
  • susceptibility to malignant hyperthermia (MH)
  • previous malignant hyperthermia (MH) episode
  • positive family history
  • increased minute ventilation
  • elevated core temperature
  • muscle rigidity
Full details

Other diagnostic factors

  • tachycardia
  • decreased urine output
  • excessive sweating with exercise
  • muscle cramps
  • spontaneous episodes of severe muscle stiffness
Full details

Risk factors

  • exposure to potent inhalation anesthetic and/or succinylcholine
  • susceptibility to Malignant hyperthermia (MH)
  • previous malignant hyperthermia (MH) episode
  • positive family history
  • exertional heat illness
Full details

Diagnostic tests

1st tests to order

  • discontinuation of inhalation anesthetic
  • exhaled carbon dioxide, oxygen consumption (inspired-expired oxygen concentration difference)
  • venous blood gases
  • serum electrolytes
  • serum creatinine
  • therapeutic trial of intravenous dantrolene
  • creatine kinase
  • urinalysis
  • urine myoglobin
  • platelets
  • prothrombin time
Full details

Tests to consider

  • caffeine halothane contracture test (CHCT)
  • in vitro contracture test (IVCT)
  • genetic testing
  • screen for muscle enzyme deficiencies
Full details

Treatment algorithm

ACUTE

inhalation anesthetic-induced

exercise- or heat-induced

Contributors

Authors

Christopher M. Edwards, MD

Assistant Professor

Department of Anesthesiology

University of Florida College of Medicine

Gainesville

FL

Disclosures

CME declares that he has no competing interests.

Nikolaus Gravenstein, MD

Professor

Department of Anesthesiology

University of Florida College of Medicine

Gainesville

FL

Disclosures

NG is a medical adviser/consultant for Teleflex, and has co-developed anesthesia patient safety education courses.

Acknowledgements

Christopher M Edwards and Nikolaus Gravenstein would like to gratefully acknowledge Dr Barbara W. Brandom and Dr Lena Mayes, the previous contributors to this topic.

Disclosures

LM declares that she has no competing interests. BWB has been reimbursed by the not-for-profit sponsor of the North American MH Registry (NAMHR), the Malignant Hyperthermia Association of the United States (MHAUS) for attending meetings related to the management of the NAMHR. BWB was the unpaid director of the NAMHR, until Jul 2016. BWB is also an author of a number of references cited in this topic.

Peer reviewers

Henry Rosenberg, MD

Director

Department of Medical Education and Clinical Research

Saint Barnabas Medical Center

Livingstone

NJ

Disclosures

HR declares that he has no competing interests.

Philip Hopkins, MD

Professor of Anesthesia

University of Leeds

Academic Unit of Anesthesia

St James's University Hospital

Leeds

UK

Disclosures

PH is an author of a number of references cited in this topic.

Thierry Girard, MD

Associate Professor

Perioperative Patient Safety

Department of Biomedicine

University Hospital Basel

Basel

Switzerland

Disclosures

TG declares that he has no competing interests.

Joseph Tobin, MD, FAAP, FCCM

Professor and Chairman

Department of Anesthesiology

Wake Forest University School of Medicine

Winston-Salem

NC

Disclosures

JT is an author of a number of references cited in this topic.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Hopkins PM, Girard T, Dalay S, et al. Malignant hyperthermia 2020: guideline from the Association of Anaesthetists. Anaesthesia. 2021 May;76(5):655-64.Full text  Abstract

Larach MG, Dirksen SJ, Belani KG, et al; Society for Ambulatory Anesthesiology; Malignant Hyperthermia Association of the United States; Ambulatory Surgery Foundation; Society for Academic Emergency Medicine; National Association of Emergency Medical Technicians. Special article: creation of a guide for the transfer of care of the malignant hyperthermia patient from ambulatory surgery centers to receiving hospital facilities. Anesth Analg. 2012 Jan;114(1):94-100.Full text  Abstract

Rüffert H, Bastian B, Bendixen D, et al. Consensus guidelines on perioperative management of malignant hyperthermia suspected or susceptible patients from the European Malignant Hyperthermia Group. Br J Anaesth. 2021 Jan;126(1):120-30.Full text  Abstract

European Malignant Hyperthermia Group​. Recognising and managing a malignant hyperthermia crisis (v2024). Nov 2024 [internet publication].Full text

Litman RS, Smith VI, Larach MG, et al. Consensus statement of the Malignant Hyperthermia Association of the United States on unresolved clinical questions concerning the management of patients with malignant hyperthermia. Anesth Analg. 2019 Apr;128(4):652-9. Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
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  • Guidelines

    • Recognizing and managing a malignant hyperthermia crisis
    • Consensus guidelines on perioperative management of malignant hyperthermia suspected or susceptible patients from the European Malignant Hyperthermia Group
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