Symptoms

In most cases, no signs or symptoms of susceptibility to malignant hyperthermia exist until you're exposed to certain drugs used for anesthesia.

In rare cases, people at risk of malignant hyperthermia have shown signs of a reaction after intense physical activity during excessive heat or humidity, during a viral illness, or when taking statin medication.

If you're at risk of malignant hyperthermia and you don't have a serious reaction during your first exposure to certain anesthesia drugs, you're still at risk if you receive these drugs in the future. Other anesthesia medications that don't trigger a reaction can be used instead.

Signs and symptoms of malignant hyperthermia may vary and can occur during anesthesia or during recovery shortly after surgery. They can include:

• Severe muscle rigidity or spasms
• Rapid, shallow breathing and problems with low oxygen and high carbon dioxide
• Rapid heart rate
• Abnormal heart rhythm
• Dangerously high body temperature
• Excessive sweating
• Patchy, irregular skin color (mottled skin)

When to see a doctor

If someone in your family is known to be at risk of malignant hyperthermia and you need to have anesthesia, it's important to tell your doctor and anesthesia specialist (anesthesiologist). Other drugs may be used instead.