Heatstroke is a condition caused by your body overheating, usually as a result of prolonged exposure to or physical exertion in high temperatures. This most serious form of heat injury, heatstroke can occur if your body temperature rises to 104 F (40 C) or higher.
Heatstroke requires emergency treatment. Untreated heatstroke can quickly damage your brain, heart, kidneys and muscles. The damage worsens the longer treatment is delayed, increasing your risk of serious complications or death.
Heatstroke symptoms include:
- High body temperature. A body temperature of 104 F (40 C) or higher is the main sign of heatstroke.
- Altered mental state or behavior. Confusion, agitation, slurred speech, irritability, delirium, seizures and coma can all result from heatstroke.
- Alteration in sweating. In heatstroke brought on by hot weather, your skin will feel hot and dry to the touch. However, in heatstroke brought on by strenuous exercise, your skin may feel moist.
- Nausea and vomiting. You may feel sick to your stomach or vomit.
- Flushed skin. Your skin may turn red as your body temperature increases.
- Rapid breathing. Your breathing may become rapid and shallow.
- Racing heart rate. Your pulse may significantly increase because heat stress places a tremendous burden on your heart to help cool your body.
- Your head may throb.
Causes
Heatstroke can occur as a result of:
- Exposure to a hot environment. In a type of heatstroke, called nonexertional or classic heatstroke, being in a hot environment leads to a rise in body temperature. This type of heatstroke typically occurs after exposure to hot, humid weather, especially for prolonged periods, such as two or three days. It occurs most often in older adults and in people with chronic illness.
- Strenuous activity. Exertional heatstroke is caused by an increase in body temperature brought on by intense physical activity in hot weather. Anyone exercising or working in hot weather can get exertional heatstroke, but it’s most likely to occur if you’re not used to high temperatures.
In either type of heatstroke, your condition can be brought on by:
- Wearing excess clothing that prevents sweat from evaporating easily and cooling your body
- Drinking alcohol, which can affect your body’s ability to regulate your temperature
- Becoming dehydrated by not drinking enough water to replenish fluids lost through sweating
Risk factors
- Age. Your ability to cope with extreme heat depends of the strength of your central nervous system. In the very young, the central nervous system is not fully developed, and in adults over 65, the central nervous system begins to deteriorate, which makes your body less able to cope with changes in body temperature. Both age groups usually have difficulty remaining hydrated, which also increases risk.
- Exertion in hot weather. Military training and participating in sports, such as football, in hot weather are among the situations that can lead to heatstroke.
- Sudden exposure to hot weather. You may be more susceptible to heat-related illness if you’re exposed to a sudden increase in temperature, such as during an early-summer heat wave or travel to a hotter climate. Limit activity for at least several days to allow yourself to acclimate to the change. However, you may still have an increased risk of heatstroke until you’ve experienced several weeks of higher temperatures.
- A lack of air conditioning. Fans may make you feel better, but during sustained hot weather, air conditioning is the most effective way to cool down and lower humidity.
- Certain medications. Some medications affect your body’s ability to stay hydrated and respond to heat. Be especially careful in hot weather if you take medications that narrow your blood vessels (vasoconstrictors), regulate your blood pressure by blocking adrenaline (beta blockers), rid your body of sodium and water (diuretics), or reduce psychiatric symptoms (antidepressants or antipsychotics).
Stimulants for attention-deficit/hyperactivity disorder (ADHD) and illegal stimulants such as amphetamines and cocaine also make you more vulnerable to heatstroke.
- Certain health conditions. Certain chronic illnesses, such as heart or lung disease, might increase your risk of heatstroke. So can being obese, being sedentary and having a history of previous heatstroke.
Complications
Heatstroke can result in a number of complications, depending on how long the body temperature is high. Severe complications include:
- Vital organ damage. Without a quick response to lower body temperature, heatstroke can cause your brain or other vital organs to swell, possibly resulting in permanent damage.
- Without prompt and adequate treatment, heatstroke can be fatal.
Tests and diagnosis
It’s usually apparent to doctors if you have heatstroke, but laboratory tests can confirm their diagnosis, rule out other causes for your symptoms and assess organ damage. These tests include:
- A blood test to check blood sodium or potassium and the content of gases in your blood to see if there’s been damage to your central nervous system
- A urine test to check the color of your urine, because it’s usually darker if you have a heat-related condition, and to check your kidney function, which can be affected by heatstroke
- Muscle function tests to check for serious damage to your muscle tissue (rhabdomyolysis)
- X-rays and other imaging tests to check for damage to your internal organs
Treatments and drugs
Heatstroke treatment centers on cooling your body to a normal temperature to prevent or reduce damage to your brain and vital organs. To do this, your doctor may take these steps:
- Immerse you in cold water. A bath of cold or ice water can quickly lower your temperature.
- Use evaporation cooling techniques. Some doctors prefer to use evaporation instead of immersion to lower your body temperature. In this technique, cool water is misted on your skin while warm air fanned over your body causes the water to evaporate, cooling the skin.
- Pack you with ice and cooling blankets. Another method is to wrap you in a special cooling blanket and apply ice packs to your groin, neck, back and armpits to lower your temperature.
- Give you medications to stop your shivering. If treatments to lower your body temperature make you shiver, your doctor may give you a muscle relaxant, such as a benzodiazepine. Shivering increases your body temperature, making treatment less effective.
Lifestyle and home remedies
Get to a shady or air-conditioned place
Cool off with damp sheets and a fan.
Take a cool shower or bath
Rehydrate
Don’t drink sugary or alcoholic beverages to rehydrate