Miliaria (Heat Rash)
Sweat retention (heat rash: miliaria) is a skin disease in which blockage of the sweat glands disrupts the release of sweat, so that sweat remains within the skin and causes redness and itching. Heat rash is particularly likely in young babies.

What causes heat rash?
Heat rash is usually seen after being in a hot, humid environment or after a feverish illness. In very hot and humid weather, heat rash can be seen in 30% of people. Wearing tight and synthetic clothing in particular triggers heat rash. Very intense physical activity or long periods of bed rest due to illness can cause heat rash to develop. In winter, heat rash can rarely develop as a result of wrapping up too warmly, sitting too close to heaters or using electric blankets.

In hot weather, along with increased sweating, there is an increase in a bacterium normally found on the skin called Staphylococcus epidermidis, and this bacterium produces a substance that blocks the sweat glands. The accumulation of sweat within the skin irritates the skin and causes a heat rash in the form of redness.

What are the symptoms of heat rash and where on the body does it appear?
It most often appears as red areas on the trunk; it may sometimes blister and, after scratching, may become infected and inflamed. Burning, prickling and itching occur in the reddened areas. Signs of heat rash are seen particularly in skin folds and areas where clothing rubs. In babies, rashes on the neck, groin and armpits are common. The condition occurs in 3 different forms:

Miliaria crystallina or sudamina: The sweat accumulation due to blocked sweat glands is superficial, and the tiny blisters on the skin burst easily.
Miliaria rubra: The blockage develops in the lowest part of the outer layer of the skin, and small red bumps develop on the skin.
Miliaria profunda: A blockage develops in the middle layer of the skin, and uncomfortable red swellings that cause a prickling sensation are seen.
Miliaria pustulosa: In addition to the heat rash, there is a purulent bacterial infection.

What measures can be taken to prevent heat rash?
To reduce sweating, stay in air-conditioned environments and reduce physical activity.
Avoid wearing thick, non-breathable, tight clothing and excessive use of soaps and similar products that irritate the skin.
Cosmetic products containing petroleum jelly or mineral oils should not be used.

How is heat rash treated?
Applying cold-water compresses soothes the skin.
Cold showers ease the symptoms.
Lotions containing calamine, boric acid, lanolin or menthol soothe the skin, but because they cause excessive drying, the skin needs to be moisturised.
In very severe cases, corticosteroid creams are used.
If a bacterial infection develops together with the heat rash, antiseptic or antibiotic medicines are used.

When should a doctor be consulted?
Heat rash usually subsides by cooling the skin and avoiding heat. If the symptoms last more than a few days and the redness gets progressively worse, or if the following signs of infection are seen, a doctor should be consulted:

Granulosis Rubra Nasi

Excessive sweating of the nose in a child is called granulosis rubra nasi. If the excessive sweating is accompanied by an unpleasant odour, most probably due to the presence of large amounts of organic acids, this is bromhidrosis.