Things to know about MILIARIA (Heat Rash)
Miliaria develops as the result of prolonged exposure to a hot, humid environment. Practically all infants can develop the rash, but this tendency decreases to include only about 40 percent of adults. Under extreme, chronic tropical conditions, however, susceptibility to miliaria may include 70 to 90 percent of adults.
Heat rash is caused by the obstruction of the sweat gland ducts; these ducts rupture and sweat escapes into the skin. Diagnosis of an individual case as one of the three recognized types of miliaria depends upon the level within the skin at which the duct is blocked.
Miliaria crystallina occurs when the duct is obstructed at the surface of the skin. Sweat accumulates just under the most superficial layer of the skin, resulting in a tiny, clear, fragile blister. There is no redness and the blisters, which usually rupture easily and are short-lived, produce no discomfort. This condition is not common and is sometimes seen in bedridden individuals, in association with a high fever. It often occurs after mild damage to the epidermis, such as sunburn.
Miliaria rubra (prickly heat) is the common, familiar form of heat rash. It is the only type of miliaria associated with redness and itching. The level of obstruction of the sweat duct is a little
deeper than in miliaria crystallina. The eruption favors the trunk and neck and spares the palms, soles, and face, and consists of small bumps and blisters, often on a flat, red spot. The bumps do not develop at the site of hair follicles, in contrast to folliculitis. Prickling, burning, and itching sensations are associated and may be severe.
These annoying symptoms are often episodic and can be provoked by any situation that produces sweating. Pustules and secondary infection may occur in extensive or chronic cases.
Miliaria rubra is very common in hot, humid environments. It is usually several months before the rash appears in these conditions, but it sometimes develops after only a few days. Miliaria rubra may appear on areas covered by clothing in hot, dry conditions. Chronic miliaria rubra may eventually result in the third type of heat rash -miliaria profunda.
In miliaria profunda, which is uncommon, obstruction of the sweat duct is at the deepest level of the three types of miliaria.Small, pale, multiple bumps appear on the trunk. The rash looks somewhat like goose flesh, but hair follicles are not involved.
There is no itching, burning, or redness. Severe miliaria rubra or profunda can result in impaired sweating, high temperatures, heat exhaustion, and eventual collapse.
Treatment Guide for Heat Rash
Miliaria crystallina is asymptomatic and resolves spontaneously without treatment. Miliaria rubra, the most common form of heat rash, will not resolve unless the individual is removed to a cool environment. Drying powders, lotions such as calamine, and anhydrous lanolin have been used with limited benefit. Air-conditioned sleeping quarters provide considerable relief.
Prevention of Heat Rash
Prevention consists of avoiding environments which induce or aggravate miliaria. Those with a history of miliaria are more . likely to have it again.
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