5 Things You Need to Know About Heat Rash

1. What is Heat Rash?

Heat rash is a common condition. It occurs when your skin overheats and itchy bumps develop. In temperate climates, it usually happens in the summertime, but in tropical climates, it can occur all year round. The rash can develop anywhere you have sweat glands, but it is most common on the back and chest. It can look like red bumps or like water blisters (see the different types of heat rashes below). The rash is often itchy or prickly (hence its other name, "prickly heat") and can sometimes burn or tingle.

2. Note the Causes of Heat Rash

The itchy bumps are the result of sweat being trapped in the eccrine ducts, the sweat ducts of your skin. There are several reasons why the sweat glands may become blocked. It may be that excess humidity has limited the evaporation of sweat from your skin. Excess sweat "backs up," blocking the duct. Normal bacteria on your skin may release a sticky substance in hot, humid conditions and clog the sweat ducts to cause a backup of sweat in the gland. Lying on your back or stomach physically blocks the ducts. This is why heat rash is more common in patients who are bedridden, babies who cannot flip over and in people who sleep in hot rooms without air conditioning.

3. Different Types of Heat Rash

The medical term for heat rash is miliaria, and there are several types. The mildest form is called miliara crystalline. This rash appears as tiny, clear blisters on the chest or back. Since there is no inflammation, itching and redness usually aren't associated with this type.

The second type of heat rash, milaria rubra, is also the most common. It is what people think of when they say they have heat rash or prickly heat. This rash can occur on the chest or back and in skin folds, such as under your arms, beneath the breasts, or in the folds of your arms and legs. In this type of rash, blockage of the sweat ducts leads to inflammation which causes red bumps that are often extremely itchy.

A third type of heat rash is called miliaria pustulosa. In this variant, pustules (small pockets of pus) form in the affected areas. It is a less common form of heat rash.

The fourth type of heat rash is miliaria profunda. This variant usually follows a prolonged, severe course of common heat rash. Fortunately, it occurs only in tropical areas. The inflammation is deep in the skin and causes firm, deep bumps. It usually is not itchy.

4. Learn the Treatments

The best way to treat heat rash is to cool off. If you are hot and sweaty, get to an air-conditioned area. Once you cool off, your sweat glands stop producing sweat, and the problem will resolve. If you cannot get to an air-conditioned area, using cooling fans directly on the skin will help. Using a moisturizer that contains a mild acid, such as Eucerin's Body Creme, can dissolve the plugs in the sweat ducts, allowing the sweat to flow freely again. Also, applying a powder, such as talcum powder or even a small amount of cornstarch, can absorb the sweat and improve the condition.

Soothing, cool baths with colloidal oatmeal, an effective anti-inflammatory, can reduce the inflammation and control the itching. Anti-itch creams, such as Eucerin's Calming Creme, also help reduce itching and calm inflammation.

5. Prevent Heat Rash

The best way to avoid a heat rash is to stay cool. If your bedroom is hot and humid, consider using an air conditioner at night to keep your skin cool and dry. Or use fans which blow on your skin to help evaporate sweat. Wear loose clothing composed of breathable fabrics that allow sweat to evaporate easily. Keep an eye on babies and the elderly as they can overheat quickly.