Heat exhaustion is a severe form of

heat illness Heat illness is a spectrum of disorders due to increased body temperature. It can be caused by either environmental conditions or by exertion. It includes minor conditions such as heat cramps, heat syncope, and heat exhaustion as well as the mo ...

. It is a

medical emergency A medical emergency is an acute injury or illness that poses an immediate risk to a person's life or long-term health, sometimes referred to as a situation risking "life or limb". These emergencies may require assistance from another, qualified ...

. Heat exhaustion is caused by the loss of water and

electrolytes An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon di ...

through

sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distri ...

. 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 Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...

, elderly people and infants can get serious heat illness even at rest, if the weather outside is hot and

humid Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

, and they are not getting enough cool air. * Some drugs, such as

diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics i ...

antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provide ...

s, beta-blockers,

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

, MDMA ('Ecstasy', 'Molly'), and other

amphetamine Amphetamine (contracted from alpha- methylphenethylamine) is a strong central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. It is also commonly used ...

s 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 Firefighters in Chicago wearing rubber three-quarter boots and jacket Firefighters in Montreal in full turnout gear during a fire Bunker gear (also known as turnout gear, fire kit and incident gear) is the personal protective equipment (PPE) ...

, etc.) * Having a higher percentage of body fat *

Dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

Fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

* Some medications, like

beta blocker Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack ( secondary prevention). They are ...

s and

antipsychotic Antipsychotics, also known as neuroleptics, are a class of psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizophrenia but also in a range of ...

medicines

Signs and symptoms

Symptoms of heat exhaustion include skin tingling,

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of th ...

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...

irritability Irritability (also called as crankiness) is the excitatory ability that living organisms have to respond to changes in their environment. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessi ...

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

thirst Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drinking, drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmol ...

weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

, vomiting, high body temperature, excessive sweating, pupil dilation, and decreased urine output.

Treatment

First aid

First aid First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial i ...

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 drink Sports drinks, also known as electrolyte drinks, are functional beverages whose stated purpose is to help athletes replace water, electrolytes, and energy before, during and especially after training or competition. There are many perceived bene ...

s 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 An emergency medical technician (EMT), also known as an ambulance technician, is a health professional that provides emergency medical services. EMTs are most commonly found working in ambulances. In English-speaking countries, paramedics are ...

(EMTs), doctors, and/or nurses may also: * Provide supplemental

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

* Administer

intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...

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 Heat stroke or heatstroke, also known as sun stroke, is a severe heat illness that results in a body temperature greater than , along with red skin, headache, dizziness, and confusion. Sweating is generally present in exertional heatstroke, ...

References

{{reflist Effects of external causes Wilderness medical emergencies