Definition of Miliaria

Miliaria are small bumps that form on the skin in environmental conditions of high heat and humidity, when the body produces much sweat that cannot evaporate and instead pools on the surface of the skin.

The bumps may be red (miliaria rubra) or clear and filled with fluid (miliaria crystallina). Clothing may further inhibit sweat evaporation. The pooling creates irritation and inflammation that obstructs the sweat glands. Most miliaria, commonly called heat rash, improves with self-care to cool the body, which causes the sweat glands to decrease production.

The skin bumps generally go away in three to five days. Newborns are particularly susceptible to miliaria in the first week or two of life. Miliaria also sometimes occurs in people who have high fevers.


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