Heat Illness: Signs, Symptoms, Risk Factors, and Prevention

Heat Illness - Signs, Symptoms, Risk Factors, and Prevention

As a physician, I prepare for everything and do my best to prevent the worst from happening. Unfortunately, heat illness can occur from temperature and humidity. The spectrum of the two creates a dangerous atmosphere for anyone spending time outdoors. In this article, I’ll review what you need to know about heat illness, including signs, symptoms, risk factors, and prevention.

What is heat illness?

Heat illness is a spectrum of disorders including heat rash, heat edema, sunburn, heat tetany, heat syncope, heat cramps, heat exhaustion, and heat stroke.

I use the word spectrum because any one of these can lead to another.

  • A heat rash is red and blotchy, can be itchy, and is usually between two areas of the skin rubbing together. It can show up anywhere on the body.
  • Heat edema is swelling of the body, usually occurs during a period called “acclimatization”. Acclimatization lasts about 1 week as a person transitions from a cooler to a hotter climate.
  • Sunburn – yes, sunburn – is considered heat illness! Sunscreen at a minimum of SPF 30 on the body and SPF 50 on the face should be worn every day spent outdoors.
  • Heat tetany is small, continuous cramps of the hands or feet.
  • Lastly, heat syncope is fainting or passing out due to the heat.

In all cases of heat illness, it is important to get out of the heat as quickly as possible!

RELATED: 10 Basic First Aid Practices That Can Save Lives

The big three of heat illness

So let’s get into the big three of heat illness. Heat cramps, heat exhaustion, and heat stroke. Besides getting out of the heat, it is important to immediately intervene with these in order to prevent progression to the next level.

1) Heat cramps

Heat cramps are muscle pain or spasms, just like a regular cramp, but much more intense and prolonged than a typical nighttime cramp. They are usually preceded by heavy sweating during intense exercise, which causes the loss of the body’s electrolytes (sodium, potassium, etc).

To intervene you should immediately stop physical activity and move to a cool place. From there, you should drink a sports drink (if available) or water to replete the body’s hydration levels, and perform prolonged stretch of the muscle that’s cramping. Be sure to get medical help right away if the cramps last longer than 1 hour, you’re on a low sodium diet, or have known heart problems.

2) Heat exhaustion

Heat exhaustion is the next level of heat illness. Typically you can see any one or all of these symptoms: heavy sweating, cool pale clammy skin, fast weak pulse, nausea or vomiting, muscle cramps, tiredness or weakness, dizziness, headache, and/or fainting.

As with heat cramps, first, move to a cool place, loosen clothing, sip water, and begin rapid cooling. Again get medical help right away if you are throwing up, symptoms get worse, or symptoms last longer than an hour.

Note: Rapid cooling options include removal of excess clothing, wet the body with water, direct fan usage, ice in the neck and groin, create an ice-cube burrito (which is exactly like it sounds), or sit in an ice bath.

3) Heat stroke

Heat stroke is a medical emergency! If you see these symptoms call 911. Heat stroke consists of the following: high body temperature (104F or higher), hot red wet skin in younger persons or cool dry skin in elderly persons, fast strong pulse, headache, dizziness, nausea, hyperventilation, confusion (disorientation, inappropriate behavior), loss of consciousness with progression to delirium, seizure, coma or death.

After calling 911, check the victim’s temperature and assess a person’s ABCs (airway, breathing, circulation). If stable, move to a cooler place, begin rapid cooling, oral (if possible) or IV rehydration, and check blood levels for electrolyte abnormalities.


Heat illness risk factors

It is important to remember that everyone is susceptible to heat illness, not just athletes that are practicing outside during the hottest part of the day.

There are many risk factors for heat illness. They include: high humidity levels (no clouds, no wind), male population, obesity, acute illness, fever, dehydration, poor fitness level, lack of acclimatization (to a new weather pattern), prescription drug use, heart disease, mental illness, poor circulation, sunburn, poor nutrition, lack of sleep, alcohol use, extremes of age (toddlers and elderly), history of heat-related illness, and sickle cell trait.

Heat illness and sickle cell trait

Most people have heard of sickle cell disease, but are you aware that it’s possible to have sickle cell trait as well? Those with sickle cell trait inherit it from their parents but do not typically have anemia or experience any pain. These individuals are more susceptible to heat illness and progress quickly, so it’s incredibly important to intervene. Extremes of heat and high altitudes also increase their risk of heat illness.

1 in 12 African American descent individuals have sickle cell trait and 1:2,000-10,000 Caucasians are also positive for the trait.

Symptoms of sickle cell trait include fatigue, muscle cramping or weakness, shortness of breath, mental status changes or dizziness, inability to continue exercise, and potential collapse.

The best treatment is prevention. This includes acclimatizing to heat and altitude progressively (usually takes about 1 week), avoid dehydration and overexertion, gradual progression in workout intensity, and longer recovery periods between repetitions and workouts.

Heat illness prevention

Speaking of preventing, I highly recommend you stay cool during the hot summer heat! Choose lightweight, light-colored, loose-fitting clothing, stay in air-conditioned place whenever possible, practice in the morning or evening hours, rest in shady areas, wear sunscreen, avoid hot and heavy meals, and pace yourself. If you feel heart pounding or gasping for breath? STOP! Get to a cool, shaded area and rest.

In addition to staying cool, it’s also important to stay hydrated! Drink plenty of fluids (before, during and after exercise), don’t wait until you’re thirsty. Avoid sugary and very cold drinks. Sports drinks will replace salt and minerals (electrolytes) after sweating, but BE CAREFUL if you have diabetes, high blood pressure or other medical conditions.

Lastly, stay informed! Heat illness is easy to stop progression if you keep an eye on each other! Know the signs and symptoms, watch the weather alerts for extreme heat, and monitor those that are high risk. 

If you have any questions, talk to your local physician.


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Dr. Shannon Carroll was raised in Baltimore, MD where she attended Maryvale Preparatory School. She graduated from Clemson University with a Bachelor of Science in Health Science in 2009. She has worked in Endocrinology, Weight Loss & Management at the Greater Baltimore Medical Center. She attended William Carey University College of Osteopathic Medicine where she graduated with a Doctor of Osteopathic Medicine degree in 2015. She is currently completing her Family Medicine Residency as chief resident at Nassau University Medical Center in Long Island, NY. She practices in all areas of primary care, but takes special interest in Sports Medicine and Emergency/Urgent Care. Outside of work, she loves to spend time with family and friends, staying active and exploring NYC on the weekends, and traveling anywhere a plane can fly for vacation!