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Do Hot Temperatures Cause Eczema? Find out...

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Heat can cause skin rashes. But eczema patients regularly complain of not only rashes during hot weather but also severe itching as well as skin reddening and dryness. This article discusses how hot temperatures can aggravate eczema through heat, sweating and drying out the skin. Find out what heat does to your skin, why your eczema gets worse when it is hot outside, what you can do about it and how to use sunlight to improve your eczema symptoms without getting another flare-up.

How We Perceive Heat

Heat is perceived through the thermoreceptors in the skin. Thermoreceptors are sensory (sense) receptors as well as cutaneous (skin) receptors. These means that they are a sub-type of skin receptors for perceiving touch.

In humans, the receptors for perceiving warmth are differentiated from those for perceiving cold by their unmyelinated (unsheathed) fibers and low conduction velocity.

The first stage of perceiving is, therefore, through the warmth thermoreceptors in the skin. The electrical signal generated is then passed on to the spinal cord which transmits it to the brain (thalamus).

Temperature regulation happens in the hypothalamus of the brain. For example, in response to high temperatures (or hot weather), the hypothalamus can signal various parts of the body to help reduce the impact of higher temperatures.

To this end, the core temperature of the body will drop and the sweating will be triggered to help cool the skin.

Can Heat Cause Eczema?

High temperatures in the form of hot weather especially when combined with high humidity can cause eczema.

Multiple studies and patients’ reports clearly demonstrate that extreme and abrupt changes in temperature can trigger eczema flare-ups, especially in children. Observations also indicate that eczema is more common during the summer months than during the winter.

Other causes of heat besides weather include

  • Tight-fitting and non-breathable clothing
  • Long journeys in vehicles that are not well aerated and are without functional climate control
  • Heated rooms in the house, workplace, school, etc.
  • Intense exercises

Heat-induced eczema breakout can result in the formation of puss-filled blisters on the skin as well as the reddening of the skin. Heat can also trigger inflammation and itching.

Besides directly causing eczema, hot temperatures cause the skin to dry out and also trigger sweating.

Dry skin and sweating are two known triggers of eczema. When the skin gets dry, it cracks and wrinkles.

These effects of heat on the skin are caused by water loss in skin cells as well as in the deep tissues of the skin. Dryness damages the skin and creates the ideal environment for pathogens and toxins to cause further damage to the skin.

Sweating can also irritate the skin. Instead of moisturizing the skin, sweat washes up irritants to the skin surface where they further aggravate the skin.

In addition, the salt content of sweat can also irritate the skin and dry it out.

How Heat Causes Eczema

Hot temperatures

  • tighten the skin
  • creates micro-fissures in the skin
  • cause photo-aging of the skin
  • creates the ideal environment for bacterial colonization of the skin
  • dry out the skin
  • cause the reddening of the skin
  • induce profuse sweating that leaves the skin damp instead of moisturizing it
  • irritates the skin and induces itching

Preventing Heat-Induced Eczema

There are different techniques for reducing the impact of heat on the skin for eczema patients. Discussed below are the most important advice for avoiding and treating heat-induced eczema.


Wearing comfortable clothes is the first rule of keeping cool during hot days. Light, soft, breathable clothes made out of natural fibers are recommended for keeping heat out and encouraging proper ventilation for your skin.

Therefore, you should avoid synthetic fabrics because these are usually heavy and do not promote proper airflow to help the skin cool.

In addition, heavy fabrics such as wool may irritate the skin. The best choices for eczema patients for lowering skin temperature are cotton clothing.

For an infant, wearing two light clothes instead of one heavy cloth is better because the top one can be removed when it gets hot. Also, while traveling, you should dress an infant for the trip rather than the destination. This is important because it can get hot in the vehicle.

Lastly, refrain from wearing thick or many clothes to bed. This is because heat can quickly build up while you are under covers. Heat is not restricted to daytime and nighttime sweating can trigger eczema flare-ups too.


Bathing can keep the skin cool but hot baths should be avoided. Even when it is cold, tepid water instead of warm water should be used.

To prevent sweat from irritating the skin, showering immediately after exercising or strenuous activities is recommended. Showering helps rinse the skin and can remove other irritants besides sweat. Besides a full-body bath, rinsing the skin after exposing it to potential irritants such as pollen and sand is recommended.

Swimming should be done with care as the chlorine in pool water can irritate the skin.

Where taking your bath is impossible, apply wet, cold compresses to the area of the skin affected by eczema to help keep it clean, moisturized and cool.

Lastly, it is important to drink water when it is hot. Even when indoors, heat can still dry out the skin. Therefore, drinking water keeps the body and skin hydrated as well as to help lower the body’s core temperature.

Avoid caffeinated drinks because caffeine is a diuretic that promotes water loss through urination.

Skin Care

After taking a bath, the moisture on your skin gets removed by toweling or through evaporation. Therefore, it is important to lock in moisture in the skin immediately after taking a bath.

Moisturizes are recommended for this purpose and they are effective for lowering the temperature of the skin and for preventing skin dryness through water loss.

When choosing a moisturizer, make sure to pick a hypoallergenic moisturizer that has no chemical irritants.

Using a hypoallergenic sunscreen is also important for keeping the heat of sun exposure from drying up and damaging your skin. Because sunscreens keep out ultraviolet radiation from reaching the skin, they may reduce vitamin D production in the body.

However, sunscreens are essential for keeping your skin cool and moisturized especially if you spend time outdoors.

Lastly, you should keep a faithful skin care regimen which includes regular application of moisturizer and sunscreen.

Temperature Control

While you may not be able to control temperatures outdoors, the range of temperature indoors is usually within your control.

To keep your home or workplace cool, you should try air conditioning. In addition, keep your thermostat settings low to avoid dry air from getting to your skin.

Furthermore, when you are in a heated room during cold weather, avoid sitting anywhere near the source of heat.

Make sure that whatever you are using to lower the temperature of your environment does not dry out your skin. Therefore, do not cool your skin with sources of dry wind. Try cool mist humidifiers instead.

Phototherapy, Sunlight, and Eczema

Even though the increased hours of sunlight during the summer can trigger eczema, sun exposure can also help in the treatment of the skin condition.

In fact, health experts regularly recommend increased sun exposure and phototherapy in the treatment of eczema. And this advice is backed by strong support from multiple clinical studies.

Therefore, it may seem paradoxical that sunlight, a heat source, can both heal and trigger eczema.

However, it is both true that while hot temperatures can trigger eczema, ultraviolet light of certain wavelengths can help eczema. While heat can dry out and irritate the skin, the increased production of vitamin D in the skin promoted by sun exposure can relieve eczema.

All of this means that while ultraviolet radiation of sunlight is good for eczema, the accompanying heat is bad for the skin disease.

Therefore, it is advised that eczema patients restrict their exposure to sunlight to less than an hour daily and only when the sun is not at its peak.

Alternatively, phototherapy can be used by eczema patients to improve their skin condition. Narrowband ultraviolet light (UVA and UVAB) can increase vitamin D production in the skin while not significantly raising its temperature.

Phototherapy can raise serum vitamin D levels. This is important because vitamin D deficiency is common among eczema patients.

Vitamin D improves eczema by its antimicrobial, antioxidant and anti-inflammatory properties.

Studies on Heat and Atopic Eczema

Abnormal Reaction to Heat in Eczema Patients

A 1998 study published in a German medical journal of dermatology investigated the differences in response to heat between eczema patients and healthy subjects. The researchers found out that the skin reacts differently to heat when it is affected by eczema.

For the study, the researchers recruited 21 patients with atopic eczema and 23 healthy controls.

For each of these study participants, they exposed the skin of the forearm on one arm to a cold bath (17 – 18 degrees Celsius) and later to a warm bath (40 – 41 degrees Celsius) for 15 minutes each. Then, the researchers noted the skin temperature of the other arm for each exposure.

The results of the study showed that eczema patients had a rather rigid and different reaction to temperature than normal subjects.

The researchers, therefore, concluded that atopic eczema may cause abnormal thermoregulation in the skin.

The result of this study is significant because it indicates that patients with atopic eczema may not be able to regulate their skin temperatures well enough. Therefore, hot temperatures may cause more skin damage in these patients because the body does not compensate for the heat with some cooling countermeasures.

Such impaired thermoregulation in eczema may be responsible for the itching, redness, rashes and local inflammation triggered in the skin by high temperatures.

Weather, Itch, and Eczema

A 2001 study published in the International Journal of Biometeorology investigated the impact of weather conditions on the symptoms of atopic eczema.

By collating data from patients with atopic eczema in Davos, Switzerland over a period of 7 years, the researchers looked for relationships between 15 weather variables and the symptoms of these patients. They found that the eczema symptom with the most significant correlation to weather conditions was itching.

The results of the study found that itching was related to the following meteorological factors

  • air temperature (strongly linked)
  • hours of sunshine
  • air pressure
  • water vapor pressure

The researchers found that eczema patients experienced the greatest relief during weather conditions falling within a range of temperatures and humidity that promotes moisture retention and coolness in the skin.

The results showed that when the weather was too hot (or too cold) and too dry (or too wet), itching was experienced.





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