What Is Heat Intolerance? Here's Why You May Be More Sensitive to Hot Weather Than Others

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 US National Library of Medicine (MedlinePlus). In other more severe cases, extreme heat can also lead to heat illness, like heat cramps, heat exhaustion, and heat stroke.

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, tells 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.

What are the symptoms of heat intolerance?

One common sign of heat intolerance is increased sweating, Chantel Strachan, MD, an internist at ColumbiaDoctors and Columbia University Irving Medical Center, tells Health. However, heat intolerance can show up as more than just extreme sweatiness in some people. While it can vary between people, Dr. Strachan says some of the more common signs of heat 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, One Medical West Coast regional medical director, tells Health. Of course, many of these symptoms also apply to other conditions, so speak with your physician 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 the 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. Strachan and Dr. Bhuyan, like being a younger child or 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. Axene says 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.

How can you treat heat intolerance—and prevent it in the first place?

When it comes to heat intolerance, preventing flare-ups is key. Dr. Axene stresses 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," adds Dr. Axene.

According to MedlinePlus, if you are in a very hot environment, you can work to prevent heat illness emergencies by drinking plenty of fluids, keeping inside temperatures comfortable, and limiting the time you spend outside. Dr. Strachan also recommends wearing loose, light-colored clothing, limiting alcohol, using air conditioning and fans, and carry cold packs.

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 your physician about potential lifestyle or medication-related changes you can make to help reduce your risk. Your doctor may also be able to provide more targeted advice based on your symptoms and location.

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