Heat Rash (cont.)

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What does heat rash look like?

The appearance of the heat rash depends upon where the excess sweat gets deposited in the skin.

Tiny blisters that look like small beads of sweat are seen if the sweat is blocked at the most superficial layers of the skin where the sweat duct opens on the skin surface. Called miliaria crystalline, it has no symptoms other than these "sweat bubbles."

Classic heat rash or miliaria rubra occurs if the sweat causes inflammation in the deeper layers of the epidermis. Like any other inflammation, the area becomes red (and therefore the name rubra) and the blisters become slightly larger. Because the sweat glands are blocked and don't deliver sweat to the skin's surface, the area involved is dry and can be irritated, itchy, and sore. This rash is also called prickly heat.

Less commonly, after repeated episodes of prickly heat, the heat rash may inflame the deeper layer of the skin called the dermis, and cause miliaria profunda. This rash is made up of larger, harder bumps that are more skin colored. The rash begins almost immediately after exercise, and again no sweat can be found on the affected areas. Rarely, this type of heat rash may be potentially dangerous if enough skin is involved, since the lack of sweating can lead to heat-related illnesses like heat cramps, heat exhaustion, or heat stroke.

Heat rash pictures

Pictures of heat rash in children and adults
Pictures of heat rash in children and adults

Reviewed by Charles Patrick Davis, MD, PhD on 7/24/2012

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