If your body is overheating, and you have a high temperature, bumps on your skin, muscle spasms, headache, dizziness, nausea or a number of other symptoms, you may have one of the most common heat-related illnesses: heat rash, heat cramps, heat exhaustion or heat stroke. Heat illnesses range from mild to severe, and heat stroke can be deadly.
A heat illness is one caused by high temperatures and humidity. You may get an illness while exercising or working in high heat and humidity. The four most common heat illnesses include:
Your body sweats to keep itself cool. If temperatures and humidity are too high, sweating isn’t effective enough.
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The process that helps your body keep a healthy core temperature is called thermoregulation. Thermoregulation is controlled by a region of your brain called the hypothalamus. It activates receptors in your skin and other organs that cause you to lose heat and keep a normal core temperature. When your body gets really hot, it relies on sweat evaporation to dissipate heat (make the heat go away). If the heat entering your body is more than the rate of heat leaving your body, your core temperature will rise and you’ll be at risk for a heat-related illness.
Heat illnesses are categorized as either mild or severe. The mild types include:
The severe types include:
Who gets heat illnesses?
If you work outside, or inside in a hot and humid environment, you’re more likely to endure a heat illness. Examples of people who might be in such an environment include:
Additional factors that increase your risk of getting a heat illness include:
Statistics about student athletes state that there are around 9,000 cases of heat-related illnesses per year. Most occur during football season. Heat illnesses are the third leading cause of death in high school athletes.
In the U.S. Armed Forces in 2017, there were 2,163 cases.
Emergency departments saw 326,497 cases of heat-related illnesses. Around 12% of those patients were admitted into a hospital and 0.07% of that total died.
A fever is a symptom of an illness, not an illness itself. It’s a higher-than-normal body temperature, but it’s caused by an infection instead of external high heat and humidity.
No. A heat illness is not like a sunburn, which injures your skin. It’s also not like being in a house fire that may leave scars. Heat rashes don’t permanently damage your skin.
No. Cancer is not a complication of any heat illness.
Keep a careful eye on infants and young children because they’re at high-risk for a heat-related illness. Consider the following tips:
People age 65 and older are at a higher risk of heat illness, even if they’re not exercising. Reasons include:
Caretakers should familiarize themselves with the symptoms of heat illnesses so that they can recognize them quickly. Check in twice a day during a heat wave.
Make sure they stay hydrated. The signs of dehydration include dry skin and decreased urination.
As the name of the illness suggests, it’s caused by heat – excessive heat that increases your body’s core temperature. That heat could come from exercising, from being inside a hot space or from outside weather. High humidity – greater than 60% – makes sweat evaporation hard. A heat illness happens when your body is s unable to dissipate heat effectively, the balance of salt and water in your body becomes unbalanced and your temperature rises. Sweating fails to keep you cool.
The four heat illnesses are on a continuum with heat rash being the mildest and heat stroke the deadliest. Specific causes of the four illnesses include:
Some symptoms are similar between the four heat illnesses, but each also has distinctive symptoms that separate it from the other three. Pay attention to the unique symptoms so that you can tell the difference between the illnesses.
Note that heat exhaustion doesn’t affect your mental status. You should be checked by a healthcare provider.
Heat stroke is a medical emergency. It can lead to organ failure and death. Call 911 or go to the emergency room immediately if you have symptoms.
Just like how there are common symptoms between the four heat illnesses, there are also common methods of diagnosis. These methods include:
You may be able to treat mild heat illnesses yourself (heat rash and heat cramps) at home, but if the symptoms don’t go away or you have the symptoms of heat exhaustion or heat stroke, you should go to the emergency room. The treatments for the four heat illnesses include at-home remedies, outpatient treatment and inpatient treatment:
Heat illnesses are very preventable. Use the following simple steps to keep yourself from getting overheated:
Remember that your body needs electrolytes, not just water. You can get electrolytes from common sports drinks, or powders you can add to your water. Choose an electrolyte drink or solution that’s low in sugar.
Patients adequately cooled within 30 minutes will likely have an excellent outlook.
If you have heat rash, heat cramps or heat exhaustion, you should recover quickly after treatment. How long it takes you to recover depends on your age, general physical condition and how quickly you receive medical care. If you have heat stroke it may take you a few days to recover and you might be more sensitive to hot conditions for a week.
You may want to check with your healthcare provider for permission to return to work or activities.
After you’re treated for a heat illness, you may be sensitive to heat for up to a week.
When you have heat stroke you’re at a higher risk for the following diseases:
Your healthcare provider may keep you in the hospital for observation and ongoing treatment.
Fortunately, heat illnesses are temporary conditions. They won’t affect your quality of life for long, unless there are complications from heat stroke.
First, do your best to prevent the heat illness. If you do get symptoms, try to cool down within 30 minutes. If you’re within the 30 minute window, your outlook is the best.
Don’t rely on your coach, caretaker or supervisor at work to take care of you. Know the symptoms yourself and how to treat them.
Go to the emergency department if you have symptoms of heat exhaustion or heat stroke. Try to get there within 30 minutes of noticing the symptoms.
A note from Cleveland Clinic
Heat illnesses should not be taken lightly. You have to keep an eye on yourself when your body overheats. A heat rash may be troublesome, but heat stroke can be deadly. Familiarize yourself with the symptoms of heat illnesses to keep yourself and your friends and family safe in hot and humid weather.
Last reviewed by a Cleveland Clinic medical professional on 04/01/2021.
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