Heatstroke: Causes, Symptoms, and Treatment

The summer weather brings joys such as staying at the beach but can also pose health risks, including heat stroke and heat exhaustion. These heat injuries develop when the body cannot cool itself, usually due to prolonged exposure or strenuous activity in high temperatures. While a person with heat stroke should seek emergency treatment, this condition can be avoided by taking simple precautions.

There are two types of heat stroke. Exertional heat stroke can develop within hours of intense physical activity in hot weather. It can affect even young, healthy athletes if they work out in extreme heat or are in a closed, hot environment. In fact, heat stroke is the second most common cause of death in young athletes. Firefighters and other workers exposed to hot environments are also at risk.

Anyone who exercises outdoors or works in hot weather can develop heat stroke, especially individuals not used to high temperatures.

Babies and young children are also at higher risk because the brain, which controls the body temperature, is not fully developed yet. Therefore, they should not be left in a hot car.

Non-exertional heat stroke is caused by prolonged exposure to hot, humid weather and develops after 2-3 days. This type of heat stroke is more common in people with underlying medical conditions and the elderly.

For example, older adults who live in hot rooms without proper ventilation or air conditioner typically develop heat stroke after a few days.

What are risk factors?

Risk factors of developing heat stroke vary from underlying medical conditions to consumption of certain beverages:

• Skin, heart diseases, or other chronic illnesses.
• Taking certain drugs that decrease sweating.
• Dehydration caused by not drinking enough water.
• Drinking alcohol.
• Wearing too tight or too many clothes.
• Living a sedentary life, having excess weight, or having a history of heat stroke.
• Sudden temperature changes, for example, when traveling to hotter locations. The high heat index, calculated based on temperature and humidity, is also a risk factor.

What are the symptoms of heat stroke?

The warning signs and symptoms of heat stroke are similar to heat exhaustion and include:

• Dizziness, light-headedness, and weakness.
• Feeling clumsy and tired.
• Headache.
• Blurry vision.
• Muscle aches.
• Drenching sweats.
• Digestive symptoms like nausea and vomiting.

The main indicator of heat stroke is an increased core body temperature to 104 F (40C) or higher. The person affected by heat stroke is usually unaware that the body temperature is higher than normal.

In some cases, the temperature becomes so high that it exceeds the markings of a regular thermometer. Rectal temperature is more accurate than mouth or forehead temperature.

Other symptoms of heat stroke are:

• Changes in mental state or behavior, such as confusion, agitation, delirium, seizures, and even coma.
• Changes in breathing, blood pressure, and heart rate. The breathing may change and become shallow and rapid. The pulse may significantly increase, while the blood pressure may be too high or too low.
• Changes in sweating. The skin is typically hot and dry if the heat stroke is caused by prolonged exposure to hot temperatures. The skin is dry or a little moist if the heat stroke is caused by strenuous exercise. In both cases, the skin is flushed due to increased body temperature.
• Symptoms may also include throbbing headache, nausea, or vomiting.

Why seek help immediately?

Heat stroke has to be treated promptly to avoid damage to vital organs like the brain, heart, lungs, and kidneys.

The higher the body temperature, the more likely are serious complications. If the body temperature remains very high for an extended period, the risk of death also increases. The elderly, young children, and those with severe underlying conditions are more likely to experience life-threatening complications.

About 80% of people with heat stroke die if they are not treated promptly. Those who survive heat stroke may experience poor coordination, personality changes, or kidney damage for an extended period. The body temperature may fluctuate a few weeks after a heat stroke.

How is heat stroke diagnosed?

The diagnosis is suspected based on high temperature (over 104F/40C) and signs of brain dysfunction like confusion, agitation, or delirium, which are not seen in heat exhaustion.

At the hospital, doctors measure the temperature, and perform a physical examination. Lab tests may be used to evaluate the function of vital organs.

How to treat heat stroke?

• People who experience symptoms of heat stroke should seek emergency treatment. If you suspect that a person has this condition, call 911 immediately, carry the person indoors or in the shade, and use one of the cooling methods until the ambulance arrives.
• Ideally, the person affected by heat stroke should be immersed in cold water, such as a bathtub or a lake. If cold water immersion is not possible, some water can be misted over the body using a fan to blow the air.
• Covering the person with cooling blankets or applying ice packs to the neck, back, or armpits can also help.
• As over-the-counter drugs like aspirin or acetaminophen do not help reduce high temperatures associated with heat stroke, they should not be taken.
• The treatment at the hospital involves rapid cooling with water or ice and a fan while the body temperature and other vital signs are monitored. Cooled fluids can be administered using intravenous infusions. Other symptoms like seizures and coma are also treated and monitored.

How to prevent heat stroke?

Heat strokes can be prevented by taking simple precautions:

• Using sunscreen to avoid sunburns.
• Wearing sunglasses, hats, and loose, light-colored clothes in the summer.
• Staying well hydrated: choose plain water or energy drinks that contain electrolytes and avoid sugary drinks or alcohol.
• Avoid exercising or spending a lot of time outside when the weather is hot, especially if you have a chronic illness or take certain medication, i.e., for blood pressure or antidepressants.

Heat stroke is the most severe heat injury which should be treated immediately. If you or someone else experience the symptoms mentioned above, call 911 immediately.