Signs and symptoms of malignant hyperthermia reaction include a dangerously high body temperature, severe muscle spasms and a fast heart rate. In most cases, the genetic defect that causes malignant hyperthermia is inherited. It is called a pharmacogenetic disorder because the reaction is caused by specific drugs. Genetic testing can reveal whether you have these mutations.

If you have a parent, sibling or child with malignant hyperthermia, there is a 50 percent chance that you have the condition as well. Other close relatives, such as aunts, uncles and grandchildren, have a 25 percent chance. Men are more likely to have an episode of malignant hyperthermia than are women. Children with the condition also are susceptible to reactions during surgery.

Malignant hyperthermia may not trigger a reaction during a person's first surgery. However, the risk of a crisis remains for future surgeries. For those at risk of having a reaction, other safe medications are available.

In rare cases, people with malignant hyperthermia have shown signs of a reaction after intense physical activity.

Malignant hyperthermia is caused by a gene that you have at birth. If someone in your family has malignant hyperthermia and you need to have surgery, it's important to tell your doctor. Other drugs may be used instead.

Your risk of having malignant hyperthermia is higher if someone in your family has the condition. If a parent, sibling or child has the condition, you have a 50 percent chance of having it too. You have a 25 percent chance of having the condition if a close relative like an aunt, uncle, or grandchild has it. Men are more likely than women to have malignant hyperthermia. If someone in your family has malignant hyperthermia and you need to have surgery, it's important to tell your doctor. Other drugs may be used instead.