What Is Heat Intolerance?

It's not just excessive sweating. Know these key signs of intolerance to heat, who is at risk, and how to treat and prevent symptoms.

In the wintertime, people often dream of what they'll do when it gets hot again; some even travel to warmer climates to wait out the cold weather somewhere a little more pleasant. But as enjoyable as hot weather is, sometimes it can get a little too warm for our bodies—and that's when health issues can pop up.

The way humans react to heat can vary. In some cases, hot temperatures can cause heat intolerance—that's when your body becomes overheated due to a rise in the temperature in the environment around you, according to the National Library of Medicine's MedlinePlus. In other more severe cases, extreme heat can also lead to heat illness, like heat cramps, heat exhaustion, and heat stroke.

What Is Heat Intolerance? Symptoms, Risk Factors, and Ways to Relieve It , Tired Afro business woman suffering from heatstroke or hot summer flat without air-conditioner, touching her forehead, using waving fan, puts head on couch, sitting in living room at home. Overheating
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The body reacts so poorly to hot weather because, well, we just weren't made to withstand extreme heat. "Our bodies are designed to be at a constant temperature; we are called 'homeotherms,'" Erik D. Axene, MD, an emergency physician at Envision Healthcare who also serves as an EMS medical director and NFL physician in his community, told Health. "For this reason, our bodies' regulatory systems must maintain this constant, optimal temperature of around 98.6 degrees Fahrenheit, which is crucial to our organ systems. Unfortunately, when various health conditions or environmental extremes hamper our regulatory systems, we can overheat or become hyperthermic."

When it comes to any form of heat intolerance or heat illness, they're positions you don't want to put your body in knowingly. Here, experts weigh in on the symptoms of heat intolerance to watch out for, along with who's most at risk for dealing with heat intolerance and how to treat and prevent it.


One common sign of heat intolerance is increased sweating, Chantel Strachan, MD, an internist at ColumbiaDoctors and Columbia University Irving Medical Center, told Health. However, heat intolerance can show up as more than just extreme sweatiness in some people. While it can vary between people, Dr. Chantel Strachan said some of the more common signs of heat intolerance include:

  • Increased sweating
  • Lightheadedness
  • Excessive fatigue
  • Rapid breathing
  • Increased heart rate
  • Nausea
  • Mood changes
  • Headache
  • Decreased concentration

If you're suffering from heat intolerance, you may feel overheated, but others around you in a similar environment don't feel the same, Natasha Bhuyan, MD, a family medicine specialist at One Medical West, told Health. Of course, many of these symptoms also apply to other conditions, so speak with your healthcare professional if you're unsure if heat intolerance is to blame.

Who Is Most at Risk for Heat Intolerance?

There are a few different reasons why someone might be more sensitive to heat, making them heat intolerant. Those reasons, per MedlinePlus, include:

  • Use of amphetamines or other stimulants
  • Anxiety
  • Caffeine intake
  • Menopause
  • Too much thyroid hormone

There are a few other risk factors that can make you more susceptible to heat intolerance, too, according to Dr. Chantel Strachan and Dr. Natasha Bhuyan, like being a younger child or an older adult, having a more sedentary lifestyle and having been through a spinal cord injury, which can limit a person's sensitivity to temperature. Certain medical conditions, like multiple sclerosis and diabetes, can also cause dysregulation of a person's internal temperature controls, putting them at a greater risk for heat intolerance.

In addition to health conditions and habits, Dr. Erik Axene said that spending an extended amount of time in hot climates with extremely high or low humidity, at high elevations, or with prolonged sun exposure can cause a person to develop heat intolerance. This is especially true if a person is not wearing proper clothing or drinking adequate amounts of water.


When it comes to heat intolerance, preventing flare-ups is key. Dr. Erik Axene stressed the importance of listening to your body to stop heat intolerance or other heat-related illnesses. "Being prepared for known heat exposure, whether going on vacation, playing in a football game, or working in the yard, is crucial to preventing heat-related illnesses," Dr. Erik Axene added.

Heat intolerance can also be prevented by managing underlying causes. Skipping caffeinated beverages and other stimulants during hot times of the year might reduce sensitivity to heat. Natural anxiety remedies or stress-management techniques like meditation may be beneficial for people with anxiety. And if medication could be an issue, it's best to talk to a healthcare professional about options.

A Quick Review

According to the American Red Cross, you can work to prevent heat illness emergencies if you are in a very hot environment: drink plenty of fluids, keep inside temperatures comfortable, and limit the time you spend outside. If it is difficult to keep indoor temperatures at a comfortable level, you may also want to seek a cooling center on hot days.

Dr. Chantel Strachan also recommended wearing loose, light-colored clothing, limiting alcohol, using air conditioning and fans, and carrying cold packs. Trying to stay cool using a neck wrap is also an option.

Another thing to keep in mind: If you have certain medical conditions that can up your risk of heat intolerance, it's best to speak to a healthcare professional about potential lifestyle or medication-related changes you can make to help reduce your risk. A healthcare professional may also be able to give you more targeted advice based on your symptoms and location.

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