Heat exhaustion is a condition in which symptoms may include heavy sweating and a rapid pulse, a result of your body overheating. It’s one of three heat-related syndromes, with heat cramps being the mildest and heatstroke being the most severe.
Causes of heat exhaustion include exposure to high temperatures, particularly when combined with high humidity, and strenuous physical activity. Without prompt treatment, heat exhaustion can lead to heatstroke, a life-threatening condition. Fortunately, heat exhaustion is preventable.
Possible heat exhaustion signs and symptoms include:
- Cool, moist skin with goosebumps when in the heat
- Heavy sweating
- Weak, rapid pulse
- Low blood pressure upon standing
- Muscle cramps
If you think you’re experiencing heat exhaustion:
- Stop all activity and rest
- Move to a cooler place
- Drink cool water or sports drinks
Contact your doctor if your signs or symptoms worsen or if they don’t improve within one hour. If you are with someone showing signs of heat exhaustion, seek immediate medical attention if he or she becomes confused or agitated, loses consciousness, or is unable to drink. You will need immediate cooling and urgent medical attention if your core body temperature reaches 104 F or higher.
In hot weather, your body cools itself mainly by sweating. The evaporation of your sweat regulates your body temperature. However, when you exercise strenuously or otherwise overexert in hot, humid weather, your body is less able to cool itself efficiently. As a result, your body may develop heat cramps, the mildest form of heat-related illness. Signs and symptoms of heat cramps usually include heavy sweating, fatigue, thirst, and muscle cramps. Prompt treatment often prevents heat cramps from progressing to heat exhaustion.You usually can treat heat cramps by drinking fluids or sports drinks containing electrolytes (Gatorade, Powerade, others), getting into cooler temperatures, such as an air-conditioned or shaded place, and resting.
Besides hot weather and strenuous activity, other causes of heat exhaustion include:
- Dehydration, which reduces your body’s ability to sweat and maintain a normal temperature
- Alcohol use, which can affect your body’s ability to regulate your temperature
- Overdressing, particularly in clothes that don’t allow sweat to evaporate easily
Anyone can develop heat exhaustion, but certain factors increase your sensitivity to heat. They include:
- Young age or old age. Infants and children younger than four and adults older than 65 are at higher risk of heat exhaustion.
- Certain drugs. Medications that affect your body’s ability to stay hydrated and respond appropriately to heat include some used to treat high blood pressure and heart problems (beta-blockers, diuretics), reduce allergy symptoms (antihistamines), calm you (tranquilizers), or reduce psychiatric symptoms such as delusions (antipsychotics).
- Carrying excess weight can affect your body’s ability to regulate its temperature and cause your body to retain more heat.
- Sudden temperature changes. If you’re not used to the heat, you’re more susceptible to heat-related illnesses, such as heat exhaustion.
- A high heat index. The heat index is a single temperature value that considers how both the outdoor temperature and humidity make you feel. When the humidity is high, your sweat can’t evaporate as quickly, and your body has more difficulty cooling itself, making you prone to heat exhaustion and heatstroke.
Untreated, heat exhaustion can lead to heatstroke, a life-threatening condition that occurs when your core body temperature reaches 104 F or higher. Heatstroke requires immediate medical attention to prevent permanent damage to your brain and other vital organs that can result in death.
You can take precautions to prevent heat exhaustion and other heat-related illnesses. When temperatures climb, remember to:
- Wear loose-fitting, lightweight clothing.
- Protect against sunburn. Sunburn affects your body’s ability to cool itself, so protect yourself outdoors with a wide-brimmed hat and sunglasses and use a broad-spectrum sunscreen with an SPF of at least 15. Apply sunscreen generously and reapply every two hours — or more often if you’re swimming or sweating.
- Drink plenty of fluids.
- Take extra precautions with certain medications. Be on the lookout for heat-related problems if you take medications that can affect your body’s ability to stay hydrated and dissipate heat.
- Never leave anyone in a parked car. This is a common cause of heat-related deaths in children.
- Take it easy during the hottest parts of the day. If you can’t avoid strenuous activity in hot weather, drink fluids, and frequently rest in a cool spot.
- Get acclimated. Limit time spent working or exercising in heat until you’re conditioned to it. It can take several weeks for your body to adjust to hot weather.
- Be cautious if you’re at increased risk. If you take medications or have a condition that increases your risk of heat-related problems, such as a history of previous heat illness, avoid the heat and quickly act if you notice symptoms of overheating. If you participate in a strenuous sporting event or activity in hot weather, make sure there are medical services available in case of a heat emergency.