The Causes of Heat Exhaustion and How to Treat it

September 25, 2019
What are the causes of heat exhaustion? How can you recognize it? It's important to keep in mind that a thermometer doesn't always reflect the real danger of outside temperatures.

Heat exhaustion is a condition that’s characterized by a high body temperature that is over 40º C (104º F). It tends to occur in very hot environments and the causes of heat exhaustion usually include a combination of high humidity and intense physical activity.

Heat exhaustion can worsen into heatstroke, which is a much more serious and possibly even fatal condition. The last great heatwave that affected Europe in 2003 caused more than 35,000 deaths when temperatures exceeded 46 degrees Celsius.

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The Symptoms of Heat Exhaustion

The symptoms of heat exhaustion can be very nonspecific and the patient may not see the link between what is happening to them and heat, humidity, and exercise.

Upon physical exam, the patient will usually have a temperature below 40º C or it may even be completely normal. However, this is due to compensation mechanisms such as sweating.

The most common symptoms are:

  • Heavy sweating.
  • Pale and cold skin.
  • Rapid Pulse.
  • Muscle cramps.
  • Discomfort.
  • Weakness.
  • Dizziness
  • Headache.
  • Nausea and vomiting.
  • Dark urine due to dehydration.

Unlike what happens due to heatstroke, patients suffering from heat exhaustion usually maintain a normal mental state and do not typically experience confusion or loss of consciousness. These conditions are rare with heat exhaustion, although patients may feel dizzy when standing up quickly.

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What are the Causes of Heat Exhaustion?

Heat Exhaustion causes of heat exhaustion woman in bed with fan

Heat exhaustion occurs when the body tries to regulate its temperature through sweat, without success.

Basically, heat exhaustion occurs due to the body’s failure to maintain normal body temperature while in high temperature and humidity environments due to physical overexertion. The body tries to regulate the temperature through sweat, but there comes a time where that is ineffective.

In addition to water, the body also loses electrolytes such as sodium and potassium through sweat, which can cause muscle cramps and rapid heartbeat.

It is important to keep in mind that the temperature on the thermometer doesn’t always reflect the real danger of air temperatures. Even if the temperature is not excessively high, heat exhaustion can occur if there are also high levels of humidity. The heat index measures the air temperature plus the effects of humidity and this is the most important value to take into consideration. Therefore, temperatures considered tolerable can become dangerous in certain situations.

Risk factors

As in many other cases, the best solution for heat exhaustion is prevention.

In Spain, for example, companies are required by law to make work environment temperatures tolerable and appropriate. In offices and sedentary workplaces, temperatures must be between 17 and 27º C. If temperatures are below or above this range, it is considered thermal stress. However, there is a legal loophole regarding outdoor work.

Also, there are more situations and health conditions that can aggravate the effects of temperature and humidity:

  • Obesity
  • Cardiac disorders
  • Respiratory insufficiency
  • Certain medications: antibiotics, anticonvulsants, diuretics, laxatives, antihistamines, vasoconstrictors, beta-blockers, antidepressants and antipsychotics, among others, and some drugs such as cocaine and amphetamines.
Obese patient causes of heat exhaustion
Patients with obesity are more susceptible to heat exhaustion.

Workers aren’t the only ones that are at risk. Anyone who performs outdoor sports such as cycling, athletics, hiking, etc., at dangerous times of the day and without proper protection are also at risk of getting heat exhaustion.

Special attention must be paid to children and the elderly whose bodies cannot easily regulate temperature. As a result, these groups are more susceptible to heat exhaustion, even at lower temperatures and after little exposure time.

Preventive measures

  • Wear lightweight, loose-fitting, and light-colored clothes.
  • Also, wear a hat or visor or use an umbrella to prevent getting direct sun on your head.
  • Apply and reapply high SPF sunscreen, depending on where you are the time of the year and the UV index.
  • Drink enough water. Drink lots of it and make sure to drink often, after short periods. To check if you’re properly hydrated, simply observe the color of your urine: if it’s light, you are well-hydrated. However, if it’s darker, you may be dehydrated and need to drink more water.
  • Replace electrolytes that are lost next to the water by sweat. Isotonic sports drinks or a classic alkaline lemonade (lemonade with sugar, baking soda, and salt) can help.
  • Reduce intake of stimulant drinks containing caffeine like cola, coffee, etc.
  • Avoid alcohol intake as it causes dehydration.
  • As much as possible, schedule the activities that require physical exertion, whether related to sports or work, at times of the day that are less hot. Additionally, it’s also important to schedule breaks that allow you to rest in a cooler place for a few minutes before you resume your activity.
  • Under no circumstances should you ever leave children inside a car in hot weather. The temperature can rise many degrees and lead to death in a short amount of time.

What to do if you have heat exhaustion

Hydration causes of heat exhaustion

Proper hydration is key to counteracting the effects and causes heat exhaustion. Also, it’s important to find a cool place to rest.

In the case of heat exhaustion:

  • Leave places with hot temperatures and look for a cool place in the shade.
  • You can lie on the floor and raise your legs to facilitate blood flow back to the heart and brain.
  • Get rid of unnecessary clothing, unbutton any buttons on the neck or any other area that could be bothersome or constrictive.
  • Cool off with a cold bath or shower. Apply wet towels to the head, neck, and chest.
  • Slowly hydrate with water or electrolyte drinks.
  • The symptoms of exhaustion may last several days. Do not exercise or expose yourself to heat or the sun until you have fully recovered.

If after these recommendations you do not recover and your body temperature remains high or you pass out or have seizures, you should call emergency services or see a doctor immediately. It is very important to be cautious with strenuous activities and other causes of heat exhaustion. So, take the necessary preventive measures and precautions

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