Picture of Miliaria Rubra (Prickly Heat)

This is the most common form of miliaria and is a common disorder of the eccrine sweat glands that often occurs in conditions of increased heat and humidity. Miliaria is thought to be caused by blockage of the sweat ducts, which results in the leakage of eccrine sweat into the epidermis or dermis.
Image Source: Guillaume / Science Source
Text Source: Medscape
Text Source: Medscape