Heat Rash, also called Miliaria, is a common condition that occurs mostly in hot weather or whenever something triggers excessive sweat. It occurs most frequently in infants but can also be seen in adults. Fortunately, it is usually not terribly severe and will clear up on its own so there is no real cause for alarm.

This condition occurs when the sweat glands become blocked, preventing sweat from being expelled from the body normally. The sweat then becomes trapped under the skin, causing inflammation and irritation. It can appear anywhere on the body, but is more commonly found in folds of the skin, such as the area under the breasts or in the groin. Infants tend to experience it mostly around the neck and shoulders.

There are three general types of heat rash: Mliaria crystallina, Miliaria rubra and Miliaria profunda. Miliaria crystallina results in tiny blisters that are not itchy or painful and the condition usually clears up on its own. Miliaria rubra is commonly referred to as prickly heat. This form of the condition exhibits blisters that are red and itchy or have a prickly sensation. It occurs most frequently after exposure to extremely hot weather.

The third form, miliaria profunda, is more rare and occurs almost exclusively among adults who have had repeated bouts of miliaria rubra. It is characterized by flesh colored growths that may resemble goose bumps and, in some cases, a lack of perspiration.

What causes miliaria?

Prolonged exposure to perspiration can lead to plugging of the sweat ducts. This results in the duct breaking open and the escape of sweat below the skin which causes the rash. Heat and humidity are factors involved in the cause of miliaria.

There are several contributing factors that can cause the sweat ducts to become plugged. In infants the cause is immaturity. The sweat ducts are simply not developed enough to function properly. As babies age, this condition corrects itself.

Tropical climates, physical activity and wearing clothing that does not allow the skin to breathe, all of which can increase sweat levels, are common culprits among adults. The use of certain medications, such as clonidine, which are designed to increase sweat production and the use of heavy creams and ointments that can block the sweat ducts may also lead to the development of miliaria.

What’s the best treatment for heat rash?

The key to treating miliaria is simply to avoid excessive heat and humidity. Wearing loose cotton clothing will help prevent an occurrence. Cool baths and air conditioning are also very helpful. Some sufferers find that using a bath brush with soap to exfoliate the skin will decrease the occurrences of prickly heat.

Avoiding any conditions that may cause excess sweating is the primary way to prevent/treat this condition.

If the rash becomes itchy and irritating, you can use Calamine lotion to soothe it. Other medications, such as Anhydrous lanolin and topical steroids can be used to prevent duct blockage and ease the condition.

How long does heat rash last? It’s different for everyone. Most cases will resolve themselves in a matter of days. More severe cases might take up to a week or so. Treating the condition as soon as it occurs will help minimize the duration as well as the severity.

If you have a very severe case of miliaria your doctor will likely give you a prescription lotion to apply to the area. This is how to get rid of a heat rash in extreme cases.