What Causes Heat Intolerance and What You Can Do to Prevent It?

Fact checked by Olga Sadouskaya, MD
Clinical Pharmacologist, Chief Medical Officer

Are you one of those people who are always hot and sweaty, even when everyone else is feeling cold? Well, it’s not “just you”. Heat intolerance is a real medical phenomenon, a set of symptoms that can be a sign of various health conditions or a side effect of medications.

In this article, we’ll discuss what causes heat intolerance and how to manage it so that it doesn’t interfere with your quality of life.

Symptoms of heat intolerance

Heat intolerance is an unusual sensitivity to heat. People with heat intolerance feel hot when other people around them feel comfortable or even cold.

But there’s more to heat intolerance than just feeling uncomfortably hot. Some other symptoms include:

  • Excessive sweating
  • Being very tired in hot weather
  • Feeling nauseous in warm environments
  • Feeling anxious and moody when it’s too hot

Another term for heat intolerance is “heat sensitivity”. These terms are used interchangeably and refer to the same symptoms.

What can cause heat intolerance?

Sensitivity to heat can be caused by a wide variety of medical conditions.

Hyperthyroidism (an overactive thyroid)

Your thyroid is an organ at the front of your neck. It produces hormones that regulate your metabolism.

Sometimes, the thyroid becomes overactive. This condition is called hyperthyroidism. It makes your metabolism too fast, so you may experience symptoms like unexpected weight loss, a fast and irregular heart rate, nervousness and sensitivity to heat.

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Fortunately, a simple blood test can show if your thyroid is producing the right amount of hormones. Once you receive a diagnosis, your healthcare provider will find a way to treat it.

Diabetes

Diabetes refers to several health conditions where the body either doesn’t produce insulin or doesn’t respond to it correctly. Insulin is a hormone that controls how your cells and tissues absorb energy.

If diabetes isn’t managed well, it damages nerves and blood vessels.

This, in turn, can affect the sweat glands. And when a person’s body can’t make enough sweat, it’s more likely to overheat.

Diabetes is a lifelong disease (except for gestational diabetes, which only occurs during pregnancy) that needs to be managed with lifestyle changes and medications.

Your healthcare provider can run some simple tests to find out if you have diabetes.

Multiple sclerosis

Multiple sclerosis (MS) is a disease that affects the nervous system, namely the brain and the spinal cord. It has a very wide range of symptoms, from fatigue and muscle stiffness to difficulty walking and serious vision problems.

When a person has multiple sclerosis, their immune system attacks the protective sheath around their nerves. Because of this, the nerves can’t transmit signals as quickly and reliably as they used to. This can cause problems with regulating body temperature.

Up to 80% of MS sufferers report that heat causes their symptoms to worsen. In addition, MS can affect the parts of the brain that regulate body temperature, making heat intolerance even worse.

A woman walking on a beach at sunset to prevent heat exhaustion

Menopause

Women’s estrogen levels naturally drop as they age. These hormonal changes can affect the part of the brain that regulates temperature, leading to so-called hot flashes. These are sudden episodes of intense heat, often accompanied by sweating and flushing.

In addition to hot flashes, menopause can lead to a general heat intolerance. Fortunately, there are medications that can reduce these side effects of the normal aging process.

Being out of shape

People who are out of shape are more likely to suffer from heat intolerance. Fit people are typically better accustomed to the increases in body temperature caused by physical activity, so they aren’t as sensitive to heat.

Regular exercise has countless benefits and improving heat sensitivity is one of them. So if you’re not already participating in regular physical activity, it’s time to get started! Just make sure to get your doctor’s approval before starting any fitness program.

Medications that cause heat intolerance

In addition to the abovementioned health conditions, heat intolerance is a frequent side effect of certain medications:

  • Some antihistamines (allergy medications) can make you sweat less, so that your body can’t cool itself down.
  • Some blood pressure medications make your kidneys expel more fluid from your body, which increases the risk of dehydration.
  • Other blood pressure medications (known as beta-blockers) can decrease blood flow to the skin, making it harder to lose extra heat.
  • Decongestants (medications for unblocking a stuffy nose) can also limit blood flow to the skin.
  • Stimulants such as those used to treat ADHD tend to raise body temperature, making overheating more likely.
  • Antidepressants may cause heat intolerance by affecting your hypothalamus, a part of your brain that’s responsible for regulating temperature.

If you believe that your heat intolerance is caused by your medications, talk to your healthcare provider. They might be able to prescribe an alternative medication or adjust the dose in order to reduce side effects.

However, sometimes there’s no alternative to your meds so you might have to stick to your treatment and find other ways to manage your heat intolerance.

Possible effects of heat intolerance

Heat intolerance is more than just an unpleasant condition that makes you sweat a lot and engage in neverending “thermostat wars” with family members and coworkers. In fact, it can have a serious impact on your health.

Being overheated for an extended period of time can lead to heat exhaustion. Its symptoms include:

  • Dizziness
  • Confusion
  • Feeling like you’re about to pass out
  • Vomiting
  • Headaches
  • Fatigue

If left untreated, heat exhaustion can turn into heatstroke, a potentially life-threatening condition.

Also, people with multiple sclerosis notice that their vision becomes blurry when they’re overheated. Vision disturbances can be very dangerous if they happen while driving.

What to do if you’re extra sensitive to heat

Drink more fluids

Your body regulates its core temperature by sweating, and the production of sweat requires water. So make sure you provide your body with enough fluids.

It’s important to hydrate regularly, so try to carry a water bottle with you at all times. You can also boost your water intake by eating lots of vegetables and fruit (which are mostly made of water).

You don’t have to drink water all the time. Juices and drinks like tea or coffee are fine, too. You may have heard that caffeine can make your body lose water, but studies show that drinking the same amount of coffee regularly doesn’t contribute to dehydration.

A man drinking water to combat heat intolerance

Stay physically active

This sounds like terrible advice when every movement makes you sweat. However, as we’ve already mentioned, heat intolerance can be directly linked to poor cardiovascular fitness levels. By not exercising, you may be making your fitness levels decrease even further.

So it’s time to ask your doctor if you can participate in your chosen physical activity, and get started!

To avoid getting overheated, exercise when it’s relatively cool outside (such as in the mornings and evenings). If you like training at the gym, pick a time when it isn’t overcrowded and stuffy.

As you become more physically fit, you may notice that your tolerance for heat improves.

Cool your feet and hands

Some people who suffer from heat intolerance find that putting their hands or feet in cold water helps cool the entire body.

While your boss probably won’t let you sit at your desk with your feet in a bucket, you can at least go to the bathroom and wash your hands from time to time. And if you have short hair, you can even put your head in the bathroom sink!

Dress comfortably

Wear clothes made of breathable, lightweight natural fabrics like cotton or linen. Other good options are bamboo and other kinds of viscose (fabric made out of wood pulp).

If excessive sweating is a problem, you may want to wear athletic clothing.

It’s made of materials that were specifically designed to move sweat away from your body.

When choosing warm clothes, make sure they’re easy to remove when you start to feel overheated. For example, opt for cardigans instead of pullovers.

Cool down your accessories

This is a little trick for the summer months. When wearing a scarf or a fabric hat, consider placing them under running water for a few seconds so they become damp. That will cool you down when you put them on.

In addition, you can try so-called cooling necklaces (or even keep your favorite jewelry in the fridge so that it’s nice and cool when you put it on).

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Consider getting a cooling vest

If you find that simply wearing breathable fabrics doesn’t do the job for you, try wearing a cooling vest. They can be worn either under or over your clothing, depending on your preference.

Key takeaways

Heat intolerance is a set of symptoms that can be caused by a variety of medical conditions and medications. Fortunately, it can often be managed with simple lifestyle changes like drinking more fluids, wearing breathable clothing or exercising more.

If you feel that your heat intolerance is interfering with your daily life and simple measures don’t help, ask your doctor for advice. They’ll help you find the cause of your heat sensitivity and suggest more ways to reduce it.

August 11, 2022