Heat illness includes heat stroke, heat exhaustion, heat cramps, and heat rash. It often occurs when a person is exercising, working, or engaging in an activity when temperatures and humidity are high.
Heat rash and heat cramps are mild types of heat illness.
Heat exhaustion and heat stroke are serious types of heat illness.
Individuals who exercise or work under hot, humid conditions – inside or out – are at highest risk for heat illness. Exercising or working in the sun on a hot, humid day increases the risk of heat illness.
Other factors that increase the risk for heat illness include:
Some of the industries with a high risk for heat illness include construction, transportation and utilities, farming, maintenance, landscaping, and support activities for oil and gas operations. Athletes who compete outside also have an increased risk.
Normal body temperature is balanced through heat production and heat loss. A heat-related illness occurs when the body is not able to regulate, or control, its temperature. Heavy sweating disturbs the body’s normal salt-water balance, which causes the symptoms of heat illness.
Most cases of heat illness occur when a person is exercising, working, or engaging in an activity when the temperature and humidity are both high. Under these conditions, sweat cannot evaporate from the skin (the body’s natural cooling system), and the body’s temperature begins to rise. If left untreated, a heat illness can lead to serious complications, even death. If detected and treated early, however, most serious problems can be avoided.
Heat stroke is a medical emergency. Call 911 immediately if a person has any of these symptoms:
Heat stroke is the most serious form of heat illness. Heat stroke can cause blood disorders and damage to the heart, liver, kidneys, muscles, and nervous system. Heat stroke can lead to death if the person does not receive emergency medical treatment.
When a person with heat exhaustion does not receive treatment, the illness can worsen and become heat stroke. An individual with heat exhaustion is at higher risk for accidents because heat exhaustion often causes tiredness, confusion, and decreased alertness.
Call 911 immediately.
The best treatment for heat stroke is immediate cooling in an ice bath. It takes ice and water to efficiently cool the body. Do not delay. If heat stroke occurs at a location where an ice bath is not possible, move the individual to a cool area if indoors or a cool, shady area if outdoors. Loosen or remove the person’s clothing. Have the person lie down and slightly elevate the feet. Cool the person as quickly as possible. Wet the person’s skin with cool water, place cool cloths or ice all over the body, spray the person with a garden hose or soak the person’s clothes with cold water. Check the person’s temperature and continue these efforts until his/her temperature is 101°F or lower. Do NOT give the person fluids to drink. Continue your efforts until medical help arrives.
While waiting for medical help, move the individual to a cool area if indoors or to a cool, shady area if outdoors. Give the person cool water to drink in small sips. Cool head, face, and neck with cold ice packs, cold cloths or cold water. When symptoms improve, take the individual to a clinic or emergency room to be seen by a nurse or doctor.
Heat cramps usually can be treated by rest and fluids. The person should stop the activity and rest in a cool place. Have him/her drink apple or grape juice or a sports drink in small sips every 15 to 20 minutes. He or she should rest for several hours before going back to work or exercise.
Talcum powder will soothe heat rash. Do not apply lotions or ointments. To prevent heat rash from coming back, the skin must be kept dry.
People with heat rash, heat cramps, or heat exhaustion usually recover quickly after treatment. How long it takes a person to recover from heat stroke depends on the person’s age, physical condition, and how quickly he or she receives medical care. A person who has had heat exhaustion or heat stroke may be more sensitive to hot conditions for up to a week after the event. Check with your doctor before returning to work or activities.
Last reviewed by a Cleveland Clinic medical professional on 01/05/2017.