Heat exhaustion is a severe form of heat illness. It is a medical emergency. Heat exhaustion is caused by the loss of water and electrolytes through sweating. The United States Department of Labor makes the following recommendation, "Heat illness can be prevented. Remember these three things: water, rest, and shade." Causes Common causes of heat exhaustion include: Hot, sunny, humid weather Physical exertion, especially in hot, humid weather Due to impaired thermoregulation, elderly people and infants can get serious heat illness even at rest, if the weather outside is hot and humid, and they are not getting enough cool air. Some drugs, such as diuretics, antihistamines, beta-blockers, alcohol, MDMA ('Ecstasy', 'Molly'), and other amphetamines can cause an increase in the risk of heat exhaustion. Especially during physical exertion, risk factors for heat exhaustion include: Wearing dark, padded, or insulated clothing; hats; and/or helmets (for example, football pads, turnout gear, etc.) Having a higher percentage of body fat Dehydration Fever Some medications, like beta blockers and antipsychotic medicines Signs and symptoms Symptoms of heat exhaustion include skin tingling, nausea, dizziness, irritability, headache, thirst, weakness, vomiting, high body temperature, excessive sweating, pupil dilation, and decreased urine output. Treatment First aid First aid for heat exhaustion includes: Moving the person to a cool place Having the patient take off extra layers of clothes Cooling the patient down by fanning them and/or putting wet towels on their body Having them lie down and put their feet up if they are feeling dizzy Having them drink water or sports drinks unless they are unconscious, too disoriented to drink, or vomiting Turning the patient on their side if they are vomiting Emergency medical treatment If an individual with heat exhaustion receives medical treatment, Emergency Medical Technicians (EMTs), doctors, and/or nurses may also: Provide supplemental oxygen Administer intravenous fluids and electrolytes if they are too confused to drink and/or are vomiting Prognosis If left untreated, heat exhaustion may progress to heat stroke. See also Occupational heat stress Heat stroke References Effects of external causes Wilderness medical emergencies