The Effects of Heat on Health

Are you aware of the effects of heat on health? Here are 7 consequences according to scientists.
The Effects of Heat on Health
Diego Pereira

Reviewed and approved by el médico Diego Pereira.

Last update: 13 March, 2023

According to the World Health Organization (WHO), between 2000 and 2016 the number of people exposed to heat waves increased by about 125 million. In recent years, increasingly intense summers have been experienced, which has a direct impact on health. Today we’ll tell you 7 effects of heat on health so that you can be aware of them, and, if necessary, apply them to your life.

As you’d expect, the effects of heat on health are very varied, and depend on a wide variety of factors. The exposure time, the type of activity being carried out, the degree of hydration, the age, and the underlying conditions are just some of them. We review 7 most common effects of heat on your health according to experts.

7 effects of heat on health

If you have come this far, maybe you have experienced unusually high temperatures in the past year. Staying in the shade for as long as possible, using sunscreen, and drinking plenty of fluids are some of the things you can do to minimize the impact.

1. Dehydration

One of the best-known health effects of heat is dehydration. Dehydration is the process in which you lose more fluid than you take in. There are three types of dehydration: isotonic, hypertonic, and hypotonic.

Children and the elderly are more prone to it, as are those who don’t drink enough fluids during days of high temperatures. Johns Hopkins Medicine suggests the following to avoid it:

  • Schedule outdoor activities during the coolest hours of the day.
  • Drink plenty of fluids according to the temperature of the day.
  • Consider drinking sports drinks if doing strenuous activities. These help balance electrolytes.
  • Wear clothing that protects the face (sunglasses, hats) and body (long-sleeved shirts).

As you can see these are very easy tips to follow. The symptoms of dehydration can go unnoticed at first, and for this reason it’s one of the most dangerous effects of heat on health. You should watch out for dry mucous membranes, dizziness, confusion, dry skin, frequent urination, increased heart rate, and irregular breathing patterns.

2. Hyperthermia

Health effects of heat include hyperthermia
Heat hyperthermia is often confused with fever, although the pathological mechanisms involved are very different.

Hyperthermia is the general term for a sharp increase in body temperature. The clinical name is hyperthermic heat disorders, and they encompass a whole spectrum of conditions. The most serious of these is heat stroke, a condition that can be fatal. Being physically active on hot days, being over 60, wearing tight clothing, drinking alcohol excessively, and having underlying illnesses increase the risk of heat hyperthermia.

It’s important to note that heat hyperthermia is not the same as fever. When you have a fever, the body’s command center, the hypothalamus, voluntarily raises the temperature. When you have heat hyperthermia, your temperature rises regardless of what the command center “decides”. You can develop cramps, exhaustion, a rash, lightheadedness, and a headache as a result.

3. Heatstroke

Heat stroke is probably the biggest effect of heat on your health. Researchers distinguish two types: exertional heat stroke and non-exertional heat stroke.

The first case refers to heat stroke that occurs in people without disabilities who perform physical activities. The second refers to older people or those who suffer from conditions such as diabetes, obesity or heart disease.

Heat stroke, according to the Centers for Disease Control and Prevention (CDC), occurs when body temperature rises above 40°C in less than 15 minutes. This is a potentially fatal consequence, which demands immediate medical intervention. It’s often accompanied by ataxia, seizures, and delusions.

4. Heat exhaustion

As experts rightly warn, heat exhaustion is one of the most common heat-related illnesses. It’s characterized by malaise, hypotension, fatigue, vomiting, anxiety, circulatory collapse, nausea, irritability, and fainting. On average, it occurs when body temperature rises between 38°C and 40°C.

As it’s a benign effect, the best way to resolve it is to withdraw from the hot environment, drink plenty of fluids, and remove any clothing that may cause hot flashes. More severe cases require intravenous fluid replacement. Symptoms may be more intense in the presence of humidity and strenuous physical activity.

5. Irritability and mood swings

Health effects of heat include irritability
Behavioral changes may occur in the early stages of periods of intense heat.

Irritability and mood swings are effects of heat on health that manifest themselves on a subjective level. There are many ways in which heat can affects your temperament. For example, sleeping problems (due to excessive heat at night), restriction of daily activities, impotence, and lack of control over the situation.

In fact, there is evidence that heat waves worsen the symptoms of people with mental disorders. For example, those with depression, anxiety, or Alzheimer’s disease may experience an exacerbation of their symptoms. This is something that is often overlooked, and patients need to be aware of it in order to gain greater control of their conditions.

6. Heat edema

High temperatures can cause transient peripheral vascular dilatation. In conjunction with sodium imbalance from dehydration, it can cause heat edema. Those who engage in some type of physical activity during their exposure to heat may not be aware of the symptoms. Those who remain in a more sedentary state may notice their extremities swell.

7. Heat cramps

Finally, another of the effects of heat on health are heat cramps. They’re spasmodic contractions of an involuntary nature that involve large muscle groups (such as leg muscles). In essence, it occurs due to a deficiency of sodium, potassium, chloride, or magnesium.

As you can see, high temperatures have an effect on your health. Limit direct exposure to sunlight during the hottest days, and be sure to drink plenty of fluids throughout the day. Being aware of the effects of heat on health will lead you to take the necessary measures to avoid them.

  • Hansen, A., Bi, P., Nitschke, M., Ryan, P., Pisaniello, D., Tucker, G. (2008). The effect of heat waves on mental health in a temperate Australian city. Environ Health Perspect;116(10):1369-1375.
  • Hifumi, T., Kondo, Y., Shimizu, K., Miyake, Y. (2018). Heat stroke. J Intensive Care;6:30.
  • Khan, A. A. (2019). Heat related illnesses. Review of an ongoing challenge. Saudi Med;40(12):1195-1201.

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