Heat emergencies fall into three categories of increasing severity: heat cramps, heat exhaustion, and heatstroke.

Heat illnesses are easily preventable by taking precautions in hot weather.

Children, elderly, and obese people have a higher risk of developing heat illness. People taking certain medications or drinking alcohol also have a higher risk. However, even a top athlete in superb condition can succumb to heat illness if he or she ignores the warning signs.

If the problem isn't addressed, heat cramps (caused by loss of salt from heavy sweating) can lead to heat exhaustion (caused by dehydration), which can progress to heatstroke. Heatstroke, the most serious of the three, can cause shock, brain damage, organ failure, and even death.

Heat emergencies are caused by prolonged exposure to extreme heat. The following are common causes of heat emergencies:

• Alcohol use
• Dehydration
• Heart disease
• High temperatures or humidity
• Medications such as diuretics, neuroleptics, phenothiazines, and anticholinergics
• Prolonged or excessive exercise
• Sweat gland problems
• Too much clothing