Malignant fever or malignant hyperthermia is a disease that leads to a fast rise in body temperature and extreme muscle contractions when anyone with the condition gets common anesthesia. Malignant hyperthermia is handed down by generations through genes.

Hyperthermia means an elevated body temperature. This condition is not like the hyperthermia from medical emergencies such as heat stroke or infections.

Malignant hyperthermia is inherited. A single parent must have the genes for an offspring to inherit this condition.

This condition will arise with other inherited muscle diseases like multi-minicore myopathy and central core disease.

Symptoms of malignant fever include the following:

  • Bleeding
  • Dark brown urine
  • Muscle pain with no known cause
  • Muscle rigidity
  • Muscle stiffness
  • Rise in body temperature to 40.6 centigrade or greater


Malignant fever is normally found out after an individual is given anesthesia during surgery.

There should be a family history of the disease or unexplained deaths during anesthesia.

The person having this condition may have a rapid and irregular heart rate.

Assessments for malignant fever may include the following:

  • Blood tests such as prothombin time and partial thrombloplastin time
  • Blood chemistry, including CPK or creatinine phosphokinase
  • Genetic testing
  • Muscle biopsy
  • Urine testing for myoglobin, a type of muscle protein



During the episode of malignant fever, a treatment known as dantrolene may be given. Wrapping the individual in a cooling blanket can decrease body temperature and the risk of serious issues.

To preserve kidney function during an episode, the person may receive fluids thru a vein.

If you need surgery, tell both your surgeon and anesthesiologist before the surgical procedure if:

  • You or a member of your family had issues with anesthesia before
  • You have a family history of malignant fever

Using some drugs can prevent malignant fever throughout the surgical procedure.

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