A heat rash is a common skin disorder that occurs when a person sweats a lot due to physical activity or even hot environment. It appears to be a cluster of small bubbles formed just under the skin.
Although it is possible to get a heat rash in all age groups, it is most common in babies and young children.
Common symptoms
The rash commonly occurs in areas of the neck, head, and chest as well as areas where skin rubs against each other such as armpits or inner thighs. It causes a bubble-like rash (called vesicles) under the skin. This rash usually appears in clusters and may or may not be red.
The occurrence is usually associated with heat or excessive sweating and may present with itchiness and/or pain.
Heat rash commonly occurs in areas of the neck, head, and chest.
Blocked sweat glands
Heat rash occurs when the sweat glands are blocked or under-developed as in the case of babies. These sweat glands produce sweat but are blocked, hence the sweat produced are trapped under the skin forming vesicles irritating the skin which causes itching. When too much sweat is produced, and the pressure is too high, sweat glands may burst causing stinging pain.
“Miliaria crystallina”, “miliaria rubra”, “miliaria pustulosa”, “miliaria profunda”
There are many names to heat rash, but medical professionals classify heat rash under four different names reflecting their appearances and causes.
Miliaria crystallina refers to blocked sweat glands that are closest to the surface of the skin. The vesicles formed are white and the fluid contained within them is clear. It is usually not itchy.
Miliaria rubra (also commonly known as prickly heat) occurs deeper from the surface of the skin when compared to miliaria crystallina. The vesicles appear larger and are red in colour. The surface can feel dry and itchy. It also produces a prickling, painful sensation where the name prickly heat arose from.
Miliaria pustulosa is similar to miliaria crystallina except that the vesicles appear yellowish instead of being white and the fluid contained within them is pus-like which suggests bacterial infection.
Miliaria profundal occurs even deeper under the skin when compared to miliaria rubra. This occurs after multiple bouts of miliria rubra and the inflammation have reached a deeper layer of the skin. This presents as larger bumps that are flesh-coloured.
Self-help
A heat rash is generally benign, and a can be treated with a number of simple lifestyle changes which reduce the amount of sweat produced. There is no specific treatment for a heat rash.
- Avoid hot, humid places and stay in cool, dry locations if possible.
- Wear clothes that do not trap heat such as loose think clothes which allows the skin to “breathe”.
- Take cold baths or apply cold, wet cloth that is clean on areas affected by the rash.
Seeking professional help
Seeking a doctor’s or pharmacist’s help is usually not necessary unless you have a fever, or feel that your skin is infected such as in the case of miliaria pustulosa. Signs of infection are redness accompanied with pain (different from the prickling pain from miliria rubra) and pus discharge.
Heat rash in children
Heat rashes are common in children, particularly babies as mentioned above. There is no need to be worried and the treatment is the same as described in the self-help section.
References:
- Patient education: Heat rash (prickly heat) (The Basics) [Internet]. Uptodate.com. 2018 [cited 6 December 2019]. Available from: https://www.uptodate.com/contents/heat-rash-prickly-heat-the-basics
- Papadakis M, McPhee S, Rabow M. Current medical diagnosis & treatment 2017.
- Prose N, Kristal L, Weinberg S. Weinberg’s color atlas of pediatric dermatology.
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