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:

• Cool, moist skin with goose bumps when under hot temperature
• Heavy sweating
• Faintness
• Dizziness
• Fatigue
• Weak, rapid pulse
• Low blood pressure upon standing
• Muscle cramps
• Nausea
• Headache

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. 

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. 

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.

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.

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.

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. 

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.

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.