Skip to main content
Family of four plays at the beach with coastline in background

In hot weather, beware of dangerous heat illnesses

August 15, 2017 | UCI Health
couple exercising
Staying hydrated and wearing lightweight, light-colored clothing are two ways you can prevent heatstroke.

Do you know the difference between heat cramps, heat exhaustion and heat stroke? Do you know which one is a life-threatening medical emergency?

Heat illnesses fall along a continuum and have overlapping symptoms and signs, explains Dr. Isabel M. Algaze González, UCI Health emergency medicine physician and assistant clinical professor of emergency medicine with the UC Irvine School of Medicine.

Heat cramps and heat exhaustion

At the lowest end of the continuum are heat cramps, which are muscle spasms that occur after physical exertion in hot weather conditions.

Heat cramps can progress into heat exhaustion, which is in the middle of the continuum.

During heat exhaustion, people typically run a temperature of about 101 to 104 degrees Fahrenheit. Other heat exhaustion signs and symptoms may include:

  • Sweating profusely
  • A racing pulse
  • Feeling dizzy and weak
  • Cramps
  • Headaches
  • Nausea
  • Clammy skin
  • Fainting

When to call 911

Heat stroke falls at the most severe end of the heat-illness spectrum and demands immediate medical attention. When a change in behavior appears along with the previous symptoms, that’s a red flag.

You need to call 911.

“The most important symptom in heat stroke that differentiates it from heat exhaustion is a change in mental status,” Algaze explains. “You may see confusion, agitation, delirium, potentially even a coma.”

If you suspect someone is suffering symptoms of heat stroke or heat exhaustion, get him or her cooled down and hydrated as quickly as possible while you wait for emergency medical help to arrive. Some of the things you can do:

  • Place the person in a cool, shaded environment.
  • Remove extra clothes.
  • Fan the person.
  • Wet the skin.
  • Place ice packs on the person or ultimately submerge the person carefully up to the shoulders in cold water, if the person is unconscious.

What happens during a heat stroke

It is important to call 911 as soon as possible to prevent organ damage from heat stroke.

Heat stroke induces an inflammatory response syndrome, like when you have an infection that spreads through the body. The response creates tissue injury, and blood is shunted to the skin and muscles, neglecting some organs more than others, but all organs may be involved, Algaze explains.

Also, when you’re in temperatures that are high enough, enzymes get “denatured” – they kind of fall apart – and don’t work like they are supposed to, she says. Also, there is increased production of heat-shock proteins.

“It’s going to feel like non-specific symptoms. You’re just feeling ‘bad’ everywhere. It’s more of a concert of everything happening together. When this damage is portrayed as a change in mental status, that is when the brain is primarily affected or when there is organ damage,” she says.

Who is most at risk for heat stroke?

While many people might expect that infants, young children, seniors and people with certain chronic conditions (such as heart disease, kidney disease or certain mental diseases) are groups most at risk for heat illnesses; athletes and people who are overweight are at risk as well.

Athletes love to push themselves to their limits and may ignore important body signals that they need to rest, Algaze says. And people who are overweight are unable to dissipate the heat as easily.

Preventing heat stroke and heat exhaustion

To protect yourself and others from a heat illness, Algaze recommends:

  • Follow weather reports, heat advisories and indexes.
  • Stay indoors.
  • Limit exposure to the sun.
  • Avoid working out or strenuous work during the hottest parts of the day, between 10 a.m. and 2 p.m.
  • Eat a well-balanced diet. Heavy meals make your body generate more heat because it is hard at work digesting. Get healthy recipe ideas ›
  • Wear lightweight, light-colored clothing to reflect the heat.
  • Avoid alcohol and caffeinated drinks; they are dehydrating.
  • Drink plenty of water. (Beware, though, of drinking too much water. Pay attention to your pee; urine should be light yellow. What color should your urine be?)
  • If dehydrated, drink beverages with electrolytes. (Kidney disease patients should check with their doctors about consuming these beverages and increasing water consumption.)
  • Take a cold shower.
  • Seek air conditioning.
  • Never leave children or pets in the car. The temperature in a car can be 40 to 50 degrees higher than outside.
  • Avoid sunburns. They hamper the body’s ability to cool itself by sweating effectively.
  • Don’t be alone. Have friends or family nearby to help you stay cool and hydrated. Monitor family and friends who might be at risk.
  • Remember that certain medications (diuretics, antihistamines, beta blockers, amphetamines, antidepressants) make you more susceptible to heat illnesses.

Related stories