Heat Exhaustion - Symptoms and Causes

Overview

Heat exhaustion occurs when the body becomes too hot. Common signs include heavy sweating and a fast heartbeat. It falls between heat cramps (mild) and heatstroke (severe) on the spectrum of heat-related health problems.

Several factors can trigger heat illness:

High temperatures
High humidity levels
Intense physical activity

Without quick treatment, heat exhaustion may progress to heatstroke, which can be deadly. The good news is that heat exhaustion can be prevented with proper precautions.

Signs of Heat Exhaustion

Heat exhaustion can come on quickly or develop slowly over time, especially during long exercise sessions.

Your body may show these warning signs:

Cool, moist skin with goose bumps even though it’s hot
Heavy sweating
Feeling faint
Dizziness
Tiredness
Weak, fast heartbeat
Drop in blood pressure when standing up
Muscle cramps
Feeling sick to your stomach
Headache

When Medical Help Is Needed

If you think you have heat exhaustion, take these steps right away:

Stop all activities and rest
Move to a cooler area
Drink cool water or sports drinks

Call your doctor if your symptoms worsen or don’t get better within one hour.

Seek emergency medical help immediately if someone with heat exhaustion becomes confused, passes out, or can’t drink fluids. If their temperature measured rectally reaches 104°F (40°C) or higher, they need immediate cooling and emergency medical attention.

Why Heat Cramps Happen

Your body has a natural cooling system. When you’re hot, you sweat. As sweat evaporates from your skin, it takes heat away and cools you down. This process helps maintain your core body temperature around 98.6°F (37°C).

However, this cooling system can fail during intense exercise or in hot, humid weather. When humidity is high, sweat doesn’t evaporate as quickly from your skin. This makes it harder for your body to release heat.

When your cooling system struggles, heat cramps may develop. These painful muscle contractions are early warning signs that your body is overheating. Symptoms often include:

Heavy sweating
Tired feeling
Strong thirst
Painful muscle cramps

To treat heat cramps, try:

Moving to a cooler area (shade or air conditioning)
Resting
Drinking fluids with electrolytes (sports drinks)

Acting quickly can prevent heat cramps from becoming more serious conditions like heat exhaustion.

Other Causes

Several factors besides hot weather and exercise can lead to heat-related problems:

Dehydration: Not drinking enough water makes it hard for your body to sweat and control temperature.
Alcohol consumption: Drinking alcohol can interfere with your body’s temperature regulation systems.
Improper clothing: Wearing too many clothes or fabrics that trap sweat can prevent proper cooling.

Your risk increases when these factors combine. For example, drinking alcohol while exercising in hot weather creates a dangerous situation for your body’s cooling system.

Risk Factors

Several factors can make a person more likely to develop heat illness:

Age Extremes

Children under 4 years old have not fully developed their body’s temperature control system
Adults over 65 may have reduced ability to regulate body temperature due to aging, illnesses, or medications

Medications and Substances

High blood pressure medications (beta blockers, diuretics)
Allergy medications (antihistamines)
Tranquilizers
Psychiatric medications (antipsychotics)
Illegal drugs like cocaine and amphetamines can raise core body temperature

Body Weight

Excess weight can interfere with the body’s cooling mechanisms by:

Retaining more body heat
Reducing efficiency of temperature regulation

Lack of Heat Adaptation

The body needs time to adjust to higher temperatures. Risk increases when:

Traveling from cool to warm climates
Experiencing early heat waves
Not having previous exposure to hot conditions

Environmental Conditions

High heat index (combination of temperature and humidity) makes cooling more difficult:

When humidity is high, sweat cannot evaporate effectively
The body struggles to cool itself naturally
A heat index of 91°F (33°C) or higher requires special precautions

Anyone experiencing symptoms of heat-related illness should seek cooler conditions and consider medical attention if symptoms are severe or persistent.

Complications

Untreated heat exhaustion can progress to heatstroke, a dangerous condition. Heatstroke occurs when body temperature rises to 104°F (40°C) or higher.

Without prompt care, heatstroke can cause permanent damage to:

Brain
Vital organs

This damage can be fatal. Emergency medical help is essential when symptoms of heatstroke appear.

Prevention

Heat exhaustion can be avoided with proper precautions. Taking steps to protect yourself when temperatures rise can keep you safe and healthy.

Dress Appropriately

Wear lightweight, loose-fitting clothes that allow your body to cool naturally. Tight clothing prevents proper cooling and can increase your risk of overheating.

Sun Protection

Sunburn reduces your body’s cooling ability. When outdoors, wear:

Wide-brimmed hat
Sunglasses
Broad-spectrum sunscreen (SPF 15+)

Apply sunscreen generously and reapply every two hours, more frequently when swimming or sweating.

Stay Hydrated

Drinking plenty of fluids helps maintain normal body temperature and supports sweating, your body’s natural cooling system.

Medication Awareness

Some medications can affect how your body responds to heat. Be extra careful in hot weather if you take medicines that influence hydration or temperature regulation.

Vehicle Safety

Never leave anyone in a parked car during warm weather, even briefly. Car temperatures can rise by 20°F in just 10 minutes when parked in the sun. This risk exists even with cracked windows or parking in shade. Keep vehicles locked to prevent children from entering unattended.

Activity Management

During hot weather:

Schedule strenuous activities during cooler parts of the day (morning or evening)
Take frequent breaks in cool areas
Rest often when active in heat

Gradual Adjustment

Allow your body time to adjust to hot weather. People not accustomed to heat face higher risks. It may take several weeks for your body to properly acclimate to higher temperatures.

Special Risk Considerations

Take extra precautions if you:

Have a history of heat-related illness
Take medications that increase heat sensitivity
Have certain medical conditions

For athletic events in hot weather, ensure medical services are available to respond to heat emergencies.

Heat Protection Strategy

Strategy	Action
Clothing	Wear loose, light fabrics.
Hydration	Drink fluids consistently.
Timing	Avoid midday heat (10am-4pm).
Acclimatization	Gradually increase heat exposure.
Monitoring	Watch for early warning signs.