COVID-19 Resources & Information | Testing | Vaccination | Visitor Policy and Hours
View All Services
Find a New Primary Care Provider
Search by Specialty
View All Locations
Discover classes, events, tours, and groups that fit your interests.
Home > Be Healthy > Health Library > Heat-Related Illnesses
A healthy body temperature is maintained by the nervous system. As the body temperature goes up, the body tries to stay at its normal temperature by transferring heat. Sweating and blood flow to the skin (thermoregulation) help us keep our bodies cool. A heat-related illness occurs when our bodies can no longer transfer enough heat to keep us cool.
A high body temperature (hyperthermia) can develop quickly in extremely hot environments, such as when a child is left in a car in the summer heat. Hot temperatures can also build up in small spaces where the ventilation is poor, such as attics or boiler rooms. People working in these areas may quickly get hyperthermia.
High temperature caused by a fever is different from a high body temperature caused by a heat-related illness. A fever is the body's normal reaction to infection and other conditions, both minor and serious. Heat-related illnesses produce a high body temperature because the body can't transfer heat as well as it should or because there's too much external heat gain.
Heat-related illnesses include:
Often, environmental and physical conditions can make it hard to stay cool. Heat-related illness is often caused or made worse by dehydration and fatigue. Your risk goes up if you exercise during hot weather, work outdoors, and don't wear lightweight or loose-fitting clothing for the environment. Drinking alcohol also increases your risk of dehydration.
Many medicines increase your risk of a heat-related illness. Some medicines decrease the amount of blood pumped by the heart (cardiac output) and limit blood flow to the skin, so your body is less able to cool itself by sweating. Other medicines can change your sense of thirst or make your body produce more heat. If you take medicines regularly, ask your doctor for advice about hot-weather activity and your risk of getting a heat-related illness.
Other things that may increase your risk of a heat-related illness include:
Many things can affect how your body responds to a symptom and what kind of care you may need. These include:
You have answered all the questions. Based on your answers, you may be able to take care of this problem at home.
Exposure to a hot environment can cause many problems. Problems can be mild, like a heat rash, swelling in the hands or feet, or heat cramps. But heat can also lead to more dangerous situations like confusion, seizures, or passing out.
Symptoms of heat exhaustion may include:
Heat exhaustion may occur when you are sweating a lot (typically, while working or exercising in hot weather) and do not drink enough to replace the fluids you've lost.
Symptoms of difficulty breathing can range from mild to severe. For example:
Severe trouble breathing means:
Moderate trouble breathing means:
Mild trouble breathing means:
If you have symptoms of heat exhaustion, try the following first aid to cool off:
Signs that heat exhaustion is becoming severe include:
Some other symptoms of heat-related illness include:
Symptoms of heatstroke may include:
Heatstroke occurs when the body can't control its own temperature and body temperature continues to rise.
Based on your answers, you may need care right away. The problem is likely to get worse without medical care.
Based on your answers, you need emergency care.
Call 911 or other emergency services now.
Sometimes people don't want to call 911. They may think that their symptoms aren't serious or that they can just get someone else to drive them. Or they might be concerned about the cost. But based on your answers, the safest and quickest way for you to get the care you need is to call 911 for medical transport to the hospital.
Based on your answers, you may need care soon.
Call your doctor today to discuss the symptoms and arrange for care.
Try First Aid for Symptoms
If your symptoms get better, you may not need to seek care today.
Based on your answers, you may need care soon. The problem probably will not get better without medical care.
While you wait for help to arrive:
When recognized in the early stages, mild heat exhaustion can be treated at home.
Heat syncope (fainting) usually doesn't last long. It improves when you lie down in a flat position. It's helpful to lie down in a cooler environment.
Heat edema (swelling) is treated with rest and by raising the level of your legs. If you are standing for a long time in a hot environment, flex your leg muscles often. This can keep blood from pooling in your lower legs, which can lead to heat edema and fainting.
Heat cramps are treated by getting out of the heat and replacing fluids and salt.
Heat rash (prickly heat) usually gets better and goes away without treatment.
Acclimation helps you remain active in a hot environment with less risk of a heat-related illness. You can acclimate yourself to a hot environment by gradually increasing the amount of time you exercise in the heat each day. Do this over 8 to 14 days. Adults usually need daily exercise periods that last 1 to 2 hours to become acclimated. Children need 10 to 14 days to acclimate.
You can also start acclimating while in cooler environments by wearing more clothing when exercising. This will raise the body temperature, which helps the body start sweating.
Acclimation helps you sweat for a longer time at a lower body temperature. Although this increases the amount you sweat, it decreases the amount of salt you lose in sweat or urine.
Call a doctor if any of the following occur during self-care at home:
You can help your doctor diagnose and treat your condition by being prepared for your appointment.
Current as of:
March 9, 2022
Author: Healthwise StaffMedical Review: William H. Blahd Jr. MD, FACEP - Emergency MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family Medicine
Current as of: March 9, 2022
Author: Healthwise Staff
Medical Review:William H. Blahd Jr. MD, FACEP - Emergency Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine
To learn more about Healthwise, visit Healthwise.org.
© 1995-2022 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.