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How extreme heat affects your body

By The Health News Team | Updated July 11, 2023
Woman feeling the sun's heat

Recently, the National Weather Service (NWS) issued an excessive heat warning for areas of San Diego County. The warning stated that “dangerously hot conditions" are possible, and that extreme heat significantly increases the potential for heat-related illnesses.

“Heat-related illnesses are on the rise as temperatures rise,” says Dr. James Elia, medical director of the Sharp Grossmont Hospital Emergency Department. “We continue to see many cases in the emergency room. Living in a warm climate such as San Diego puts our population at risk, despite being a coastal city.”

According to Dr. Elia, the high temperatures often experienced throughout San Diego are especially concerning for the aging population. “Older adults and people with cardiovascular or neurologic disorders are at higher risk, simply because the temperature regulating mechanism becomes less effective with time and disease,” he says.

How body temperature is controlled

Body temperature is regulated by the hypothalamus region of the brain. The brain works with the nervous system to regulate the dilation, or opening, of the blood vessels to allow more blood flow to the skin. This allows body heat, via body fluids and salts, to be expelled throughout the pores and evaporate into the air.

“If a person becomes too dehydrated and has expelled a significant amount of fluids through sweat, they no longer have body fluid to sweat out and have lost the ability to regulate heat,” Dr. Elia says. “This will then cause the body temperature to soar if they are still in a hot environment. This rapid increase in temperature can then cause heatstroke.”

What’s more, when the combination of dry-air heat and humidity — known as the wet-bulb temperature — exceeds the temperature of the body, sweat cannot evaporate. “At this point, an individual can no longer cool themself down.” Dr. Elia says.

Preventing heat stroke

The NWS recommends San Diegans monitor the latest weather forecasts and warnings for updates. To avoid heat-related illnesses, drink plenty of fluids, stay in an air-conditioned indoor space, and stay out of the sun.

You should also check up on relatives and neighbors. Additionally, young children and pets should never be left unattended in vehicles, especially in warm or hot weather, when car interiors can quickly reach lethal temperatures.

Most importantly, it's essential to be able to recognize dehydration and heat exhaustion to prevent the progression to heat stroke.

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 pulse

  • A high temperature of 100.4° F or above

  • Being very thirsty

If someone has heat exhaustion, Dr. Elia advises the following four steps:

  1. Move them to a cool place.

  2. Get them to lie down and raise their feet slightly.

  3. Have them drink plenty of water. Sports or rehydration drinks are also OK.

  4. Cool their skin by spraying or sponging them with cool water and fanning them. Cold packs placed around the armpits or neck are also effective.

“Stay with them until they're better,” Dr. Elia says. “They should start to cool down and feel better within 30 minutes.”

Signs of heatstroke

Finally, it's essential to continue to watch someone with heat exhaustion for additional symptoms of heatstroke, including:

  • Sweating stopped, but they still feel hot

  • Nausea or vomiting

  • Rapid heartbeat

  • Intense headache, much more severe than what one normally feels when spending time in the sun

  • Feeling hot, with bright red skin

  • Seizure

“If a person with heatstroke is left untreated, they can have many of their organs go into failure,” Dr. Elia says. “This can cause death or permanent injury. Call 911 and take them to an emergency room immediately.”

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