Heatstroke – Symptoms and Causes

Overview

Heatstroke occurs when the body overheats, typically reaching temperatures of 104°F (40°C) or higher. This dangerous condition usually results from prolonged exposure to high temperatures or excessive physical activity in hot weather.

Heatstroke represents the most severe form of heat-related illness, following milder conditions like heat exhaustion.

Most common during summer months, heatstroke demands immediate emergency medical attention. Without prompt treatment, it can rapidly damage vital organs including the brain, heart, kidneys, and muscles.

The severity of organ damage increases with delayed treatment, raising the risk of serious complications or death.

Signs of Heat Illness

Heat illness shows up in several ways. The main sign is a body temperature over 104°F (40°C). When someone has heat illness, they might seem confused or agitated.

Their speech may become unclear. In severe cases, seizures or coma can happen.

Sweating patterns change during heat illness. In hot weather, skin often feels hot and dry. But if exercise caused the heat illness, the person might sweat heavily.

Other signs include:

• Feeling sick or throwing up
• Red skin as body temperature rises
• Fast, shallow breathing
• Rapid heartbeat from the body working hard to cool down
• Throbbing headache

When to Get Medical Help

Call 911 right away if you think someone has heat illness. While waiting for help to arrive, take steps to cool the person down:

1. Move them to a shady or indoor area
2. Take off extra clothing
3. Cool them using available methods:
   • Place in cool water (tub or shower)
   • Spray with a garden hose
   • Wipe with cool water
   • Fan while spraying with cool water
   • Put ice packs or wet towels on their head, neck, armpits, and groin

Don’t wait to see if symptoms improve on their own. Heat illness needs immediate treatment to prevent serious complications.

Causes

Heatstroke occurs when body temperature rises dangerously high and can develop in two main ways.

1. Nonexertional (Classic) Heatstroke

   • Results from exposure to hot, humid environments
   • More common in older adults and people with chronic health conditions
   • Develops gradually, often after extended heat exposure

2. Exertional Heatstroke

   • Caused by strenuous physical activity in hot weather
   • Can affect anyone exercising in heat
   • More likely to occur in people not acclimated to high temperatures

Contributing Factors:

• Clothing choices – Heavy or tight clothing prevents sweat evaporation, reducing the body’s natural cooling ability.
• Alcohol consumption – Impairs the body’s temperature regulation mechanisms.
• Dehydration – Insufficient fluid intake to replace sweat losses makes it harder for the body to cool itself.

The body normally cools itself by sweating, but in certain conditions, this cooling system may fail. When this happens, body temperature rises quickly, potentially causing damage to the brain and other vital organs.

Risk Factors

Several factors can increase your chance of developing heatstroke:

Age-Related Vulnerability

• Young Children: Their nervous systems are still developing.
• Adults over 65: Their bodies respond less effectively to temperature changes.
• Both groups often struggle with staying hydrated.

Physical Activity in Hot Conditions

Military training and sports like football or marathon running in hot weather can lead to heatstroke, especially without proper hydration and rest breaks.

New Exposure to Heat

People who experience sudden temperature changes—like early summer heat waves or traveling to hotter climates—face higher risks. It takes several days to adjust to new temperatures and several weeks to fully adapt.

Lack of Cooling Systems

While fans provide some relief, air conditioning is much more effective at reducing both temperature and humidity during hot weather. Limited access to air conditioning significantly increases risk.

Medications That Increase Risk

Some medicines affect how your body manages heat:

• Vasoconstrictors (narrow blood vessels)
• Beta blockers (for blood pressure)
• Diuretics (water pills)
• Antidepressants and antipsychotics
• ADHD stimulants
• Illegal drugs like amphetamines and cocaine

Health Conditions

Certain ongoing health issues make heat more dangerous:

• Heart disease
• Lung conditions
• Being overweight
• Physical inactivity
• Previous history of heatstroke

Understanding these risk factors can help you take appropriate precautions during hot weather, especially if you fall into one or more high-risk categories.

Complications

Heatstroke can lead to serious health problems if not treated quickly. The longer body temperature stays elevated, the more dangerous it becomes.

Damage to vital organs is a significant risk. When body temperature remains high for too long, the brain and other important organs may swell. This swelling can cause permanent damage that doesn’t improve with time.

Without fast and proper treatment, heatstroke can be fatal. The high internal temperature disrupts normal body functions and can lead to death if medical help isn’t received promptly.

Prevention

Staying safe from heatstroke requires taking simple but important steps. You can avoid this dangerous condition by planning ahead and making smart choices during hot weather.

Dress Appropriately

Wear clothes that are loose and light. Tight clothes trap heat and prevent your body from cooling down properly. Choose fabrics like cotton, linen, silk, or hemp which allow air to flow and help keep you cool.

Shield Your Skin

Sunburn reduces your body’s cooling ability. When outside:

• Wear a wide-brimmed hat
• Use sunglasses to protect your eyes
• Apply broad-spectrum sunscreen (SPF 15+)
• Reapply sunscreen every 2 hours, or more often when swimming or sweating

Stay Hydrated

Drinking enough fluids helps your body maintain normal temperature through sweating. Don’t wait until you feel thirsty to drink water.

Be Careful with Medications

Some medicines can affect how your body handles heat. If you take prescription medications, ask your doctor if they might:

• Reduce your ability to sweat
• Increase sensitivity to sunlight
• Affect your body’s water balance

Car Safety Rules

Never leave anyone in a parked car during warm weather. This is especially dangerous for children. Remember:

• A car’s interior temperature can rise 20°F (11°C) in just 10 minutes
• Cracked windows and parking in shade don’t make parked cars safe
• Keep cars locked when not in use to prevent children from getting in

Time Your Activities Wisely

Plan strenuous activities for cooler parts of the day:

• Early morning
• Evening
• Avoid the hottest hours (typically 10 AM to 4 PM)

If you must work or exercise in the heat, take frequent breaks in cool areas and drink plenty of fluids.

Allow Time for Adjustment

Your body needs time to get used to hot weather. This process, called acclimatization, can take several weeks. People new to hot environments face higher risks of heat-related illnesses. Gradually increase your time in the heat as your body adapts.

Know Your Risk Factors

Some people need extra caution in hot weather:

Higher Risk Groups	Why They’re Vulnerable
Older adults	Less efficient cooling systems
Young children	Bodies heat up faster than adults
People with chronic illnesses	May have reduced sweating ability
Those taking certain medications	Some drugs affect heat regulation
People who are overweight	Extra body mass can trap heat

If you’re in a high-risk group, limit heat exposure and watch carefully for early signs of overheating.

Sports and Outdoor Events

For athletic events in hot weather:

• Ensure medical services are available
• Schedule frequent water breaks
• Create cooling stations
• Monitor participants for signs of heat illness