Symptoms and signs of malignant hyperthermia include:
A dramatic rise in body temperature, sometimes as high as 113 degrees Fahrenheit
Rigid or painful muscles, especially in the jaw.
An abnormally rapid or irregular heartbeat
Rapid breathing or uncomfortable breathing
Brown or cola-colored urine
Very low blood pressure (shock)
Muscle weakness or swelling after the event
Many people who carry a gene for malignant hyperthermia will never develop symptoms.