Heat rash
Heat rash is an inflammatory disease of the sweat glands, in technical terms they are called miliaria. Other synonyms for heat rash in general usage or colloquially are: sweat rash, heat rash, heat pustules, sweat rash, summer pimple, dermatitis hidrotica and hidroa for the transparent pimples and lichen tropicus or red dog for the red, already inflamed form of heat rash. Heat rash occurs when the ducts of sweat glands become blocked. This is particularly common when the ambient temperature is warm and the humidity is high, as in the tropics. What to do to avoid heat rash and what helps if you already have it?
Heat rash in children, babies and toddlers
The itchy heat rash in small children and babies  occurs very often. The reason for this is usually too warm and airtight clothing.  Many parents are too kind to their children and don’t just wrap them up  thick when the weather is cool. Small children, in particular, find it difficult to communicate that they are too warm. Sometimes they whine or scream, but this is a non-specific signal.
So their overheating is often not noticed. Therefore, heat and heat can easily build up on the body of small children and babies, so that the sweat glands become clogged  and are hardly ventilated. In addition, bacteria can easily settle in this warm, humid environment on the skin. Heat rash can be the result.
Heat rash in adults
Heat rash can also occur in adults. They are equally common in both sexes. Although the cause is usually a stay in tropical areas, not only a vacation in hot areas can be the trigger for the heat rash.
Tight-fitting clothing that prevents the sweat  from evaporating from the skin also leads to a build-up of heat on the body in our temperate latitudes,  which can cause heat pimples.
What does heat rash look like?
There are two different types of heat rash.  Heat rash can look different depending on the exact location of the blockage of the sweat glands. The typical Miliaria cristallina  are water-clear and bulging. The individual vesicles are rarely larger than a pinhead and are usually clustered close together.
These groups of heat pimples, in turn, are usually spread over a larger area. They are located on the fuselage, particularly on the welding paths, such as:
- under the armpits
- between the shoulders on the back or in the neck
- at the cleavage
This crystalline form of heat rash usually occurs without inflammation  , which is why the blisters do not show any redness. If you wipe firmly over the blisters, they burst, the blocked sweat gland is in contact with the surface of the body again and clear liquid escapes – similar to a drop of sweat.
The inflammatory form  of heat rash ( miliaria rubra  or red dog) is more conspicuous with symptoms such as red coloring and skin that is often generally reddened by scratching. Where they occur, the skin is swollen and itchy  or painful. This form of heat rash almost never occurs on the face or soles of the feet and palms and cannot be treated and removed by pressing or scratching.
Causes and development of heat rash
In contrast to sun  allergies, heat rash is not caused by an inflammatory reaction to UV rays, but by a blockage of the sweat glands caused by heat build-up. Therefore, heat rashes in winter are not impossible. The crystalline form of heat rash occurs very spontaneously when overheated. It usually goes away after a few hours and is not itchy. Because as soon as the heat build-up is over, the sweat glands are free again.
It is different with the red heat pimples. They usually only appear after staying in tropical areas for several days. Here the blockage of the glands is more severe and deeper in the skin. The sweat produced in the glands can therefore no longer appear on the body’s surface and instead spreads out within the skin. This congestion can either lead directly to inflammation or rupture the duct of the sweat gland through excess pressure, which eventually turns into inflammation.
The glands are mainly blocked by the tropical, warm, humid air, which causes the skin to swell. Together with the salt  in the sweat and the bacteria, which multiply magnificently between the skin and clothing, this provokes an inflammation in the sweat glands. Heat rash can occur.
What to do against heat rash?
There are different forms of treatment for heat rash that are used depending on the type of heat rash. In the case of crystalline heat rash, no drug treatment is usually necessary, not even in children or babies. What is important, however, is symptomatic therapy by eliminating heat build-up and a general rethinking of the type and amount of clothing.  Onion look and loose, airy clothing  are the best prevention.
If, in rare cases, the crystalline heat rash does not go away on its own, a zinc shake (Lotio zinci spirituosa) or zinc ointment can be used.
Even with the red heat pimples, drug therapy is usually not necessary. Powder or the aforementioned zinc mixture can have a soothing effect, as they keep the skin dry. If bacterial infestation and itching become too severe,  local antibiosis can also help against heat rash, which is applied in the form of creams.
