Edit concept Question Editor Create issue ticket

Heat Exhaustion

Heat exhaustion belongs to the group of the heat-related illnesses.


Presentation

The presentations common with heat exhaustion may develop suddenly or over a period of time especially after extended periods of exercise [7]. Possible symptoms and signs of heat exhaustion include the following:

Weakness
  • Signs of heat exhaustion include cool, moist, pale, ashen or flushed skin, as well as: headache nausea dizziness weakness exhaustion.[sharecare.com]
  • Furthermore, the Spearman's rho correlation coefficient for creatine kinase versus the anion gap is weak (r(s) 0.175) and is not statistically significant (P 0.073).[ncbi.nlm.nih.gov]
  • Symptoms include dry, hot, and flushed skin—dark or purple in color; dilated pupils; rapid, weak pulse; shallow breathing; and high temperature that may be in excess of 106 Fahrenheit.[hunter-ed.com]
  • Weakness. Feeling dizzy. Headache. Nausea. Vomiting can occur. Muscle cramps. Weak or rapid pulse. Causes Anything that keeps the body's natural cooling system from working right can lead to heat exhaustion and heat stroke.[healthy.net]
  • The pulse rate will be fast and weak, and breathing will be fast and shallow.[globalnews.ca]
Fatigue
  • Other signs and symptoms might include confusion or dizziness, decreased urination, nausea and vomiting, headache, fatigue/weakness and malaise. This answer provided for NATA by the Marist College Athletic Training Education Program.[sharecare.com]
  • The real problem is that of heat and humidity which produces heat exhaustion and fatigue, and irritability which comes from long hours spent running wet with sweat.[dictionary.cambridge.org]
  • "Parents are informing me that they're children feel fatigued. They're pale. They're vomiting. That's serious," Pimentel said. She bought fans for her classroom. But they circulate hot air.[hawaiinewsnow.com]
  • Johnson, Ars Technica, "It’s too soon to tell if the Great Barrier Reef’s bleaching was a catastrophe," 27 July 2018 Signs of heat exhaustion include fatigue, heavy sweating, dizziness, fainting, thirst, headache, and more. — Nina Bahadur, SELF, "Why[merriam-webster.com]
  • Symptoms of heat cramps usually include muscle cramps, sweating, thirst, and fatigue. Treating heat cramps by cooling off and drinking water or sports drinks can prevent heat cramps from progressing to heat exhaustion.[fastmed.com]
Fever
  • Brugada syndrome (BrS) as an established channelopathy can be unmasked by various triggers like drugs, fever, etc.[ncbi.nlm.nih.gov]
  • S igns and symptoms resemble those of shock and may include: Feeling faint Nausea Heavy sweating Ashen appearance Rapid, weak heartbeat Low blood pressure Cool, moist skin Low-grade fever Abdominal cramps If you suspect heat exhaustion: Get the person[tripleonecare.co.nz]
  • The person has a fever over 102 F (38.9 C). Other symptoms of heatstroke are present (like rapid pulse or rapid breathing). The person's condition does not improve, or worsens despite treatment.[mountsinai.org]
  • […] 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 or turnout gear) Having a higher percentage of body fat Dehydration Fever[en.wikipedia.org]
  • Any illness that causes weakness, fever, vomiting, or diarrhea. Treatment A heat stroke is a medical emergency. Heat exhaustion may respond to self-care measures. If not, medical care is needed.[healthy.net]
Malaise
  • Heat exhaustion is characterized by nonspecific symptoms such as malaise, headache, and nausea. Treatment involves monitoring the patient in a cool, shady environment and ensuring adequate hydration.[ncbi.nlm.nih.gov]
  • Heat exhaustion is a non–life-threatening clinical syndrome of weakness, malaise, nausea, syncope, and other nonspecific symptoms caused by heat exposure.[merckmanuals.com]
  • Other signs and symptoms might include confusion or dizziness, decreased urination, nausea and vomiting, headache, fatigue/weakness and malaise. This answer provided for NATA by the Marist College Athletic Training Education Program.[sharecare.com]
Tachypnea
  • Tachycardia and tachypnea are present. Complications of heat exhaustion include impending heatstroke and shock. Management - Remove the patient from the hot environment.[chemm.nlm.nih.gov]
  • Tachycardia, tachypnea, and normotension are common in heatstroke. Temperature also should be measured in the initial survey.[aafp.org]
Nausea
  • […] of heat exhaustion include nausea vomiting, lethargy, increased heart rate, increase temperature.[sharecare.com]
  • Heat exhaustion is characterized by nonspecific symptoms such as malaise, headache, and nausea. Treatment involves monitoring the patient in a cool, shady environment and ensuring adequate hydration.[ncbi.nlm.nih.gov]
  • Heat exhaustion is a non–life-threatening clinical syndrome of weakness, malaise, nausea, syncope, and other nonspecific symptoms caused by heat exposure.[merckmanuals.com]
  • Symptoms can include: Confusion Dehydration Fatigue Nausea Muscle aches Sweating Rapid heartbeat Taking a cool bath, moving to an air conditioned area and drinking hydrating fluids can often relieve heat exhaustion.[urgentcarewesthartford.com]
  • What else to watch out for: Heavy sweating Paleness Muscle cramps Tiredness Weakness Dizziness Headache Nausea or vomiting Fainting A cool bath or shower may help stop heat exhaustion from progressing to heat stroke.[globalnews.ca]
Vomiting
  • […] of heat exhaustion include nausea vomiting, lethargy, increased heart rate, increase temperature.[sharecare.com]
  • […] if they are too confused to drink and/or are vomiting If untreated, heat exhaustion may progress to heat stroke.[en.wikipedia.org]
  • If the child is vomiting, turn onto his or her side to prevent choking. Think Prevention! Teach kids to always drink plenty of liquids before and during any activity in hot, sunny weather — even if they aren't thirsty.[kidshealth.org]
  • DO NOT give an affected person any liquids (including salt drinks) if the person is vomiting or losing consciousness.[firstaidanywhere.com]
Loss of Appetite
  • Loss of appetite and feeling sick 4. Sweating with pale clammy skin 5. Cramps in the arms, legs and stomach 6.[sja.org.uk]
  • Check for signs of heat exhaustion The signs of heat exhaustion include: headache dizziness and confusion loss of appetite and feeling sick excessive sweating and pale, clammy skin cramps in the arms, legs and stomach fast breathing or pulse temperature[nhs.uk]
  • The symptoms of heat exhaustion include: headache, dizziness and confusion, loss of appetite and feeling sick, excessive sweating and pale clammy skin, cramps in the arms, legs and stomach, fast breathing or fast pulse, temperature of 37C or above, intense[metro.co.uk]
Hypotension
  • Despite initial presentations with severe hyperthermia, tachycardia and hypotension, only one patient with heat stroke had myocardial ischemia. The CPK isoenzymes were not indicative of myocardial damage in any patient.[ncbi.nlm.nih.gov]
  • On examination, patients appear tired, are usually sweaty and tachycardic, and may have orthostatic hypotension. Mental status is intact, unlike in heatstroke. Temperature is usually normal and, when elevated, usually does not exceed 40 C.[merckmanuals.com]
  • […] heat exhaustion include – Hot and flushed skin that appears as a fever Heavy and profuse sweating Intense thirst Dizziness and fatigue Nausea and vomiting Confusion Headaches Black outs or syncope and sudden fall of blood pressure called orthostatic hypotension[news-medical.net]
  • View/Print Table TABLE 2 Signs and Symptoms of Heat Exhaustion and Heatstroke Core Temperature* Signs Symptoms Heat Exhaustion 37 C to 40 C (98.6 F to 104 F) Anxiety Confusion Cutaneous flushing Hypotension Oliguria Pyrexia Tachycardia Vomiting Anorexia[aafp.org]
Tachycardia
  • It demonstrates that the hemodynamic changes in severe heat exposure reflect a hyperdynamic circulation with tachycardia and high cardiac output states.[ncbi.nlm.nih.gov]
  • Despite initial presentations with severe hyperthermia, tachycardia and hypotension, only one patient with heat stroke had myocardial ischemia. The CPK isoenzymes were not indicative of myocardial damage in any patient.[ncbi.nlm.nih.gov]
  • Tachycardia and tachypnea are present. Complications of heat exhaustion include impending heatstroke and shock. Management - Remove the patient from the hot environment.[chemm.nlm.nih.gov]
  • Tachycardia, tachypnea, and normotension are common in heatstroke. Temperature also should be measured in the initial survey.[aafp.org]
Orthostatic Hypotension
  • On examination, patients appear tired, are usually sweaty and tachycardic, and may have orthostatic hypotension. Mental status is intact, unlike in heatstroke. Temperature is usually normal and, when elevated, usually does not exceed 40 C.[merckmanuals.com]
Flushing
  • Symptoms include dry, hot, and flushed skin—dark or purple in color; dilated pupils; rapid, weak pulse; shallow breathing; and high temperature that may be in excess of 106 Fahrenheit.[hunter-ed.com]
  • Signs of heat exhaustion include cool, moist, pale, ashen or flushed skin, as well as: headache nausea dizziness weakness exhaustion.[sharecare.com]
  • […] increased sweating cool, clammy skin body temperature rises, but to less than 105 F (40.5 C) Of heatstroke: severe headache weakness, dizziness confusion fast breathing and heartbeat loss of consciousness (passing out) seizures little or no sweating flushed[kidshealth.org]
  • Symptoms of heat exhaustion include heavy sweating, extreme weakness or fatigue, dizziness/confusion, nausea, clammy/moist skin, pale or flushed complexion, muscle cramps, slightly elevated body temperature and fast/shallow breathing.[orange.floridahealth.gov]
Hot, Dry Skin
  • , dry skin body temperature rises to 105 F (40.5 C) or higher What to Do If your child has symptoms of heatstroke, get emergency medical care immediately .[kidshealth.org]
  • , dry skin body temperature rises to 105 F (40.5 C) or higher What to Do If your child has symptoms of heatstroke, get emergency medical care immediately.[kidshealth.org]
  • Heat Exhaustion Heat Stroke Dehydration Flushed, hot, dry skin with no sweating Fatigue Temperature of 105 or higher Weakness Severe, throbbing headache Clammy skin Weakness, dizziness or confusion Headache Seizure Nausea/vomiting Decreased responsiveness[active.com]
  • More serious is heat stroke, where you may develop a very high body temperature (105 F or more); a rapid, strong pulse; red, hot, dry skin; a throbbing headache; dizziness; and nausea.[heartmdinstitute.com]
  • Recognizing Heat Exhaustion Warning signs of heat exhaustion include: Heavy sweating Paleness Muscle cramps Tiredness Weakness Dizziness Headache Nausea or vomiting Fainting Hot dry skin Cold damp skin The skin may be cool and moist.[cchealth.org]
Increased Sweating
  • Signs and Symptoms Of heat exhaustion: increased thirst weakness and extreme tiredness fainting muscle cramps nausea and vomiting irritability headache increased sweating cool, clammy skin body temperature rises, but to less than 105 F (40.5 C) Of heatstroke[kidshealth.org]
  • Symptoms can include: increased thirst weakness fainting muscle cramps nausea and/or vomiting irritability headache increase sweating cool, clammy skin elevation of body temperature, but less than 104 F (40 C) What to Do: Bring your child to a cooler[kidshealth.org]
  • Acclimatization to hot environments usually occurs over 7-10 days and enables individuals to reduce the threshold at which sweating begins, increase sweat production, and increase the capacity of the sweat glands to reabsorb sweat sodium, thereby increasing[emedicine.medscape.com]
Insect Bite
  • At autopsy, based on macroscopic and microscopic examination, the apparent bruises were found to be hemorrhagic insect bites. No significant injuries were present and no semen was found.[ncbi.nlm.nih.gov]
Oliguria
  • View/Print Table TABLE 2 Signs and Symptoms of Heat Exhaustion and Heatstroke Core Temperature* Signs Symptoms Heat Exhaustion 37 C to 40 C (98.6 F to 104 F) Anxiety Confusion Cutaneous flushing Hypotension Oliguria Pyrexia Tachycardia Vomiting Anorexia[aafp.org]
Dizziness
  • Signs of heat exhaustion include cool, moist, pale, ashen or flushed skin, as well as: headache nausea dizziness weakness exhaustion.[sharecare.com]
  • They feel faint and dizzy. Muscle cramps in the arms, legs, or abdomen might be present. Carbo Veg : Collapse from excess heat with clamminess of the skin and stomach complaints.[homeopathycenter.org]
  • […] 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 putting wet towels on their body Having them lie down and put their feet up if they are feeling dizzy[en.wikipedia.org]
  • Symptoms of heat stroke include extremely high body temperature above 106ºF, hot and dry skin, profuse sweating, hallucinations, chills, throbbing headache, confusion/dizziness and/or slurred speech.[orange.floridahealth.gov]
  • Johnson, Ars Technica, "It’s too soon to tell if the Great Barrier Reef’s bleaching was a catastrophe," 27 July 2018 Signs of heat exhaustion include fatigue, heavy sweating, dizziness, fainting, thirst, headache, and more. — Nina Bahadur, SELF, "Why[merriam-webster.com]
Confusion
  • The earliest signs include unsteady gait and confusion. Recording of rectal temperature is essential. Skin colour, blood pressure and heart rate are not reliable diagnostic signs. The mainstays of therapy are rapid rehydration and cooling.[ncbi.nlm.nih.gov]
  • You should also call 999 if the person feels hot and dry, has a temperature of 40C or above, has rapid shortness of breath, is confused, has a seizure, loses consciousness, is unresponsive.[metro.co.uk]
  • Symptoms can include: Confusion Dehydration Fatigue Nausea Muscle aches Sweating Rapid heartbeat Taking a cool bath, moving to an air conditioned area and drinking hydrating fluids can often relieve heat exhaustion.[urgentcarewesthartford.com]
  • […] off extra layers of clothes Cooling the patient down by fanning them and 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 – but only if they are awake, not confused[en.wikipedia.org]
  • Symptoms of heat stroke include extremely high body temperature above 106ºF, hot and dry skin, profuse sweating, hallucinations, chills, throbbing headache, confusion/dizziness and/or slurred speech.[orange.floridahealth.gov]
Seizure
  • You should also call 999 if the person feels hot and dry, has a temperature of 40C or above, has rapid shortness of breath, is confused, has a seizure, loses consciousness, is unresponsive.[metro.co.uk]
  • In addition to dizziness, confusion, and nausea, those who have heat stroke may also experience seizures, fevers, and damage to their organs. Steps to Managing Heat Exhaustion Find a cool place.[doctorshealthpress.com]
  • The person goes into shock, faints, or has seizures. The person is not breathing. You also should begin CPR right away to try and revive them.[familydoctor.org]
  • Unconsciousness When to Seek Medical Care If you suspect heatstroke, if there is no improvement with the above self-care measures after an hour, if symptoms worsen, or if there are signs of shock, seizure, or loss of consciousness, seek emergency medical[skinsight.com]
  • […] vomiting irritability headache increased sweating cool, clammy skin body temperature rises, but to less than 105 F (40.5 C) Of heatstroke: severe headache weakness, dizziness confusion fast breathing and heartbeat loss of consciousness (passing out) seizures[kidshealth.org]
Irritability
  • Signs and Symptoms Of heat exhaustion: increased thirst weakness and extreme tiredness fainting muscle cramps nausea and vomiting irritability headache increased sweating cool, clammy skin body temperature rises, but to less than 105 F (40.5 C) Of heatstroke[kidshealth.org]
  • […] clothing; hats; and/or helmets (for example, football pads or turnout gear) Having a higher percentage of body fat Dehydration Fever Some medications, like beta blockers and antipsychotic medicines Symptoms of heat exhaustion include nausea, dizziness, irritability[en.wikipedia.org]
  • The real problem is that of heat and humidity which produces heat exhaustion and fatigue, and irritability which comes from long hours spent running wet with sweat.[dictionary.cambridge.org]
  • Irritability and confusion might be present. Veratrum alb : Individual might have fainted or collapsed. Face is pale with profuse and clammy sweat, extreme coldness especially to hands and feet. Pulse is rapid and weak.[homeopathycenter.org]
Stupor
  • Heat stroke Warm, dry skin high fever, usually over 104 F (or 40 C) Rapid heart rate Loss of appetite Nausea Vomiting Headache Fatigue Confusion Agitation Lethargy Stupor Seizures, coma, and death are possible Move to a cool place and rest.[hopkinsmedicine.org]
  • Heat stroke Warm, dry skin High fever, usually over 104 F (or 40 C) Rapid heart rate Loss of appetite Nausea Vomiting Headache Fatigue Confusion Agitation Lethargy Stupor Seizures, coma, and death are possible Move to a cool place and rest.[urmc.rochester.edu]

Workup

Diagnosis is straightforward in cases of heat exhaustion as the symptoms are immediately visible to medical experts [8]. To rule out a heat stroke however, the temperature of the patient may be taking to confirm diagnosis. When heat exhaustion has already progressed to heat stroke, there are some additional tests required. These may include:

  • Blood tests to confirm low blood sodium and potassium as well as the constituents of the bloods gaseous components. It can also be used to check for rhabdomyolysis
  • Urine test to confirm the concentration and composition of your urine and also to confirm kidney function.
  • Imaging tests to confirm presence or absence of damage to internal organs. 
Hyponatremia
  • Electrolyte levels should be measured to exclude severe hyponatremia in patients who have had excessive free water intake, particularly if they develop findings of brain dysfunction.[merckmanuals.com]
  • Clinically significant hyponatremia often results from voluntary overhydration and can be dangerous. 20 Clinical manifestations of hyponatremia include nonspecific symptoms involving the central nervous system, such as dizziness, nausea, and malaise,[aafp.org]

Treatment

Most of time, heat exhaustion can be treated without recourse to medical experts. This can be achieved by doing any of the following [9]:

  • Resting in cool environments
  • Intake of cold liquids
  • Application of cool water to the skin
  • Removal of unnecessary clothing

Within an hour of these treatment measures, the patient is supposed to feel relieved. When this is not the case, medical aid should be sought.

Common treatments used by medical experts include the use of intravenous fluids, immersion in cold water, use of ice packs and cooling blankets. 

Prognosis

Majority of heat exhaustion cases pass off without any major damages. An important step to recovery is the recognition of symptoms before a stroke occurs [6]. If the activity is stopped early enough, hydration will begin and the chances of complications occurring will be greatly reduced.

Etiology

Heat exhaustion is seen when an individual exercises and works in a hot environment and the body is not able to cool off adequately [2]. Dehydration sets in when there is water loss as a result of excessive sweating and this causes muscle cramps, weakness, nausea and vomiting. When this happens, consumption of enough fluid to replenish the body becomes difficult. The increased lack of water inhibits more sweating, evaporation and cooling.

Relative humidity is a very important factor in the development of heat exhaustion [3]. When humidity is excessively high, the sweat on the skin cannot evaporate into the surrounding air and this leads to the failure of body temperature cooling.

Inhabitants of hot environment are also predisposed to heat exhaustion. Again, in the event of a heat wave, the elderly or isolated and incapacitated individuals are at the risk of a heat exhaustion due to inability to access air conditioning.

Epidemiology

Heat exhaustion and related ailments has a high incidence in the United States and there is an average of 334 deaths per year as a result of this spectrum of illnesses [4]. Internationally, heat exhaustion incidence is poorly documented as it is rarely seen in most parts of the globe especially the tropics.

Sex distribution
Age distribution

Pathophysiology

Although there is a marked variation in ambient temperatures, humans as well as other mammals are able to maintain a particular body temperature by the natural ability to balance out heat gain with heat loss [5].

Heat exhaustion and other related illnesses ensue when heat gain firmly overwhelms the body’s mechanisms of heat loss. Excessive heat leads to important physiologic changes such as denaturation of proteins, destabilization of phospholipids and lipoproteins and liquefaction of membrane lipids. These lead to cardiovascular collapse, multiple organ failure and death. There is no exact temperature at which cardiovascular collapse can occur. This is because there are a variety of factors that can contribute to or delay organ dysfunction.

Prevention

Heat exhaustion and heat-related illnesses can be avoided by taking any of these preventive steps when temperature is high [10]:

  • Always wear loose fitting, lightweight and light coloured clothing.
  • Avoid sunburn by using umbrellas and sunscreen when going out.
  • Always stay in an environment cooler than the outside temperature especially when staying in a place for long.
  • Consume plenty of fluids to help the body stay hydrated all the time. However, alcoholic beverages must be avoided and medical advice must be sought if already dealing with a condition that requires reduction in liquid intake. 
  • Seek medical advice if you are taking any medications that make you susceptible to heat exhaustion. 
  • Avoid excessively hot spots and do not drive in a hot car. Allow the car to cool off before getting in to drive. 
  • If you travel to a hot environment, allow the body a few weeks to get used to the heat before getting into any strenuous activities. 

Summary

Heat exhaustion refers to one part of an ailment group known as heat-related illnesses [1]. This illness spectrum starts with heat cramps, before progression to heat exhaustion and heat stroke at the last. The natural cooling system of the body involves sweating but this can only be when there is enough fluid in the body for sweat production, circulation of air over the skin, and low air humidity which can allow sweat to evaporate.

With activities in a hot environment, the body becomes overwhelmed losing the innate ability to cool itself. This triggers heat-related symptoms.

Patient Information

Heat exhaustion is a condition known for the heavy sweating and rapid pulse that comes with it. It is often as a result of the body overheating. It is among the three heat-related syndromes with heat cramps being the mildest and heatstroke being the most severe of the lot.

The main cause of heat exhaustion is exposure to high temperatures especially in combination with high humidity and strenuous physical activity. When treatment is not sought, heat exhaustion may lead to heatstroke which is a life-threatening condition. Heat exhaustion is preventable though.

References

Article

  1. Maron BJ, Doerer JJ, Haas TS, et al. Sudden deaths in young competitive athletes: analysis of 1866 deaths in the United States, 1980-2006. Circulation 2009; 119:1085.
  2. Mueller FO, Cantu RC. Catastrophic sports injury research: twenty-sixth annual report. University of North Carolina, Chapel Hill 2008.
  3. Rav-Acha M, Hadad E, Epstein Y, et al. Fatal exertional heat stroke: a case series. Am J Med Sci 2004; 328:84.
  4. Roberts WO. Exertional heat stroke during a cool weather marathon: a case study. Med Sci Sports Exerc 2006; 38:1197.
  5. Capacchione JF, Muldoon SM. The relationship between exertional heat illness, exertional rhabdomyolysis, and malignant hyperthermia. Anesth Analg 2009; 109:1065.
  6. Armstrong LE, Casa DJ, Watson G. Exertional hyponatremia. Curr Sports Med Rep 2006; 5:221.
  7. Bouchama A, Knochel JP. Heat stroke. N Engl J Med. Jun 20 2002;346(25):1978-88.
  8. Costrini A. Emergency treatment of exertional heatstroke and comparison of whole body cooling techniques. Med Sci Sports Exerc. Feb 1990;22(1):15-8.
  9. Dahmash NS, al Harthi SS, Akhtar J. Invasive evaluation of patients with heat stroke. Chest. Apr 1993;103(4):1210-4.
  10. Easterling DR, Meehl GA, Parmesan C, Changnon SA, Karl TR, Mearns LO. Climate extremes: observations, modeling, and impacts. Science. Sep 22 2000;289(5487):2068-74. 

Ask Question

5000 Characters left Format the text using: # Heading, **bold**, _italic_. HTML code is not allowed.
By publishing this question you agree to the TOS and Privacy policy.
• Use a precise title for your question.
• Ask a specific question and provide age, sex, symptoms, type and duration of treatment.
• Respect your own and other people's privacy, never post full names or contact information.
• Inappropriate questions will be deleted.
• In urgent cases contact a physician, visit a hospital or call an emergency service!
Last updated: 2018-06-22 09:48