There are actually four types of heat rash, all of which have medical terms most of us wouldn’t recognize or use.

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Heat rash, prickly heat, miliaria, and summer rash all refer to the same condition—an inflammation of the skin caused by blocked sweat glands. It is uncomfortable and itchy, but can be treated at home and usually goes away within a few days, with or without treatment.

Who’s at Risk?

Heat rash can affect just about anyone of any age. Those at highest risk are people who live in hot and humid climates, older adults, overweight individuals, exercisers, those who sweat a lot, and babies. It is often associated with babies because their sweat glands are not fully developed.

What Causes Heat Rash?

Sweat glands are located in the second layer of skin called the dermis. When sweat ducts are blocked, perspiration cannot get to the surface and evaporate. Instead, it gets trapped under the skin where it causes a mild inflammation resulting in a rash.

The combination of sweating heavily when exercising while wearing clothes that don’t allow the sweat to evaporate can also trigger the rash. Heat rash can even happen during the winter if people wear too much clothing or sit close enough to a fire or heater to sweat.

How Is Heat Rash Diagnosed?

There are actually four types of heat rash, all of which have medical terms most of us wouldn’t recognize or use. They are easier to remember by how the rash looks—red, white, clear, or deep.

• Red heat rash is the most common form. It called “prickly heat” because it itches and burns. The inflammation causes a reddish-colored rash.
• If the rash is white or yellow, it might be a sign of infection and a reason to have it checked by a doctor.
• Clear heat rash looks like small, clear beads of sweat on top of the skin. It is the mildest form and not likely to cause any discomfort or itching.
• Deep heat rash is caused by repeated episodes and chronically inflamed sweat glands. Deeper layers of the skin are affected and the rash may appear as large, firm bumps.

Where on the Body Does Heat Rash Appear?

The most common places for the rash to develop are creases in the skin, such as the armpits, neck, and groin, where skin rubs against adjacent skin. Wearing tight clothes can prevent sweat from evaporating, especially around the waist, chest, or groin. Bandages and heavy creams or lotions can also block sweat glands.

How Is Heat Rash Treated?

Heat rash is uncomfortable but treatable. The first step is to stay cool. The rash may disappear simply by cooling the skin. Here are some specific suggestions.

• Avoid activities that cause sweating.
• Stay in the shade when outdoors and in air-conditioned spaces when inside.
• Wear breathable clothes (loose-fitting, loose-woven, thin, moisture-wicking, quick-drying)
• Take cool showers and use mild, antibacterial soaps.
• Use over-the-counter, anti-itch medications containing calamine, menthol, or camphor to relieve symptoms.
• Be careful about oil-based skin products. They can clog up pores and make heat rash worse.

When Should I See a Doctor About Heat Rash?

See your doctor if heat rash doesn’t go away within a few days. If the area is painful, red, swollen, or warm, or if the lesions are draining, it is likely to be infected and in need of medical attention. The same goes for swollen nodes in the armpits, neck, or groin, and if you have a fever or chills.

Don’t Worry, Be Happy

Although heat rash can be uncomfortable, it is usually mild and goes away quickly. Common sense and home remedies are enough to keep the doctor away in most cases. It’s called heat rash for a reason. Stay cool.