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

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.

The following are common causes of heat emergencies:

• High temperatures or humidity
• Dehydration
• Prolonged or excessive exercise
• Excess clothing
• Alcohol use
• Medications, such as diuretics, neuroleptics, phenothiazines, and anticholinergics
• Cardiovascular disease
• Sweat gland dysfunction

The early symptoms of heat illness include:

• Profuse sweating
• Fatigue
• Thirst
• Muscle cramps

Later symptoms of heat exhaustion include:

• Headache
• Dizziness and light-headedness
• Weakness
• Nausea and vomiting
• Cool, moist skin
• Dark urine

The symptoms of heatstroke include:

• Fever (temperature above 104°F)
• Irrational behavior
• Extreme confusion
• Dry, hot, and red skin
• Rapid, shallow breathing
• Rapid, weak pulse
• Seizures
• Unconsciousness