Heat Rash, Prickly Heat, Miliara Rubra

Heat rash, also known as prickly heat or miliaria rubra, is a common skin condition, especially in tropical regions of the world.

The skin is every person’s first line of defense from the harsh outside world. It serves as a protection for you from chemical exposure, infections, and harmful ultraviolet rays. It also helps to regulate your temperature from the body by making sweat.

Sweat that shows up on your skin comes from the sweat glands that can be found all over your body (asides in your ear canals, inside the mouth, fingers, and toenails).

These sweat glands, which are tiny in size, are regulated by the brain and generate sweat that comes up to the surface through ducts on the skin, which will later evaporate and help you cool down.

What Is Heat Rash?

Heat rash, also called miliaria or prickly heat, is a mild but uncomfortable inflammation of the sweat ducts when they are clogged.

When the sweat ducts become blocked, the sweat cannot come up to the skin surface where it will evaporate. Thus the sweat becomes trapped under the skin.

The heat rash is characterized by tiny-sized, raised bumps (looking like coarse sandpaper) evenly spread across little patches of skin. The rash typically goes away by itself and resolves in a few hours to a few days.

What Are the Symptoms of prickly heat?

The common symptoms of miliaria include an itchy, bumpy, blister-like rash. In some cases, pus may gather inside fine tiny lesions on the skin’s surface.

You may also notice that your sweat gets caught beneath your skin as well, and later you start to sweat out via flesh-colored bumps. Sometimes, you may feel a burning sensation in your skin, as well as a “prickly” feeling (as if something is crawling on your skin).

Prickly heat can show up almost anywhere, but the most common body parts that are affected by it are areas that are commonly exposed to the sun like the face, hands, neck, and the elbow folds.

Areas that are affected l may also include body parts that are covered by tight clothing like the abdominal wall, thigh creases, groin, buttocks, and the flesh under the breasts

Types of prickly heat

The four major types of heat rash (miliaria) are named according to visual characteristics (the way they appear on the skin), and are discussed below:

  • Clear (miliaria crystallina),
  • White/Yellow (miliaria pustulosa),
  • Red (miliaria rubra),
  • Deep (miliaria profunda).

Clear (Miliaria Crystallina)

Miliaria crystallina, also known as clear heat rash, appear like small, transparent, or flesh-colored sweat beads on the upper layer of skin. It is often very mild and does not produce too many uncomfortable symptoms.

Red (Miliaria Rubra)

Red heat rash (miliaria rubra) is another type of prickly heat and is the most common type of skin irritation. This is the type that is specifically called “prickly heat” as a result of its intense burning and itching symptoms.

The sweat glands become blocked, and the inflammation makes the rash have a red color known as “Rubra” (that’s why it is called miliaria rubra).

White/Yellow (Miliaria Pustulosa)

When you have heat rash and pustules form under the inflamed beads, it is called white/yellow heat rash ( also called miliaria pustulosa). You may notice these pustules as the first signs of undiagnosed skin infection and need to be examined by your doctor.

Deep (Miliaria Profunda)

This is a more severe case of heat rash. If you come down with consecutive instances of heat rash, you may become vulnerable to the kind of heat rash called miliaria profunda.

With repeated episodes prickly heat, sweat glands in broader areas of the skin may become chronically inflamed and lead to damage in deeper skin layers. When this happens, large, firm bumps may appear, especially after exercise or exposure to heat.

What Are the Causes?

Blocked sweat glands are the primary cause of heat rash. A person’s sweat glands can become blocked for several reasons, but the most popular reasons include:

The skin around the neck, groin, or armpit that touches each other or rubs on opposite skin prevents sweat from evaporating.

Tight clothing around the chest, waist, abdomen, or groin that do not allow the evaporation of sweat.

Dressing up in heavy clothing that allows sweat to accumulate on the skin. Oily lotions, heavy creams, or adhesive bandages can clog a person’s sweat ducts.

Who Is At Risk?

Some individuals are more prone to prickly heat, and certain situations can make the condition very likely. These situations include:

  • Infants and newborns (especially those wearing tight-fitting clothes or diapers)
  • Older adults who do not care how much they are sweating or those who do not frequently change their wears.
  • Living in humid and hot climates
  • Working in very hot, confined spaces that promote excessive sweating

Why Are Babies at any Greater Risk of suffering from prickly heat?

Small children often get heat rash due to the fact that their sweat glands are quite immature; thus, they can’t get rid of the sweat their body produces.

This is most common when children are heavily dressed or overdressed, bundled up for cold weather, or have a fever.


A diagnosis of heat rash can be made by seeing the rash in some common skin locations, mostly after heat-related exposure.

A doctor can easily make the diagnosis with the aid of a visual examination of the skin rash. However, atypical or complicated cases of heat rash may require a confirmation from skin scrapings, skin culture, or biopsy.

Other skin conditions can imitate a heat rash including bacterial infections, allergic reactions, fungal infections, or eczema

Home Remedies

Heat rash is often self-limited, which means that it resolves by itself without any form of treatment.

The use of over-the-counter medications like hydrocortisone cream, calamine, itch preparations (Like Benadryl spray), or even sunburn lotions can be an excellent home remedy for treating the burning and itching symptoms.

Taking a cold shower is also a great way to help yourself. Try allowing your skin air-dry instead of using a towel that can be soothing. But be careful of excessive use of ointments, lotions, or heavy creams that may cause the heat rash to become worse.

Medical Treatment for heat rash

Occasionally an unattended heat rash may become infected, especially if the sufferer has scratched it open. Bacteria can easily invade the skin and lead to cellulitis infections.

Your doctor should monitor the symptoms such as swelling, redness, fever, increased pain, or pustules. Antibiotic treatment with the use of topical creams or medications swallowed by mouth may be required to treat associated infections.

Can heat rash Be Prevented?

Keeping your sweat glands from getting clogged is the surest way to prevent having heat rash. Put on loose-fitting and breathable clothing.

Always avoid working out in hot, humid weather. Keep your skin dry, especially parts like creases and skin folds where sweat can buildup. Stay in air conditioning when you can if you are prone to heat rash.

How to protect yourself when temperatures are very high

To a large extent, your body can get used to hot and humid temperatures over time. But as you gradually get used to such conditions, here are a few practical tips to avoid heat rash, as well as other illnesses that are heat-related like heat stroke and exhaustion.

Try to avoid doing any work or exercising when there is extreme heat. Take regular cooling breaks, drink enough fluids, and prevent activities if you begin to feel overheated, dizzy, lightheaded, or faint.

Before working out in hot and humid temperatures, take into account the heat index.

How Much Water Should I Drink in Hot Weather?

Drink enough liquid at all times so that your system is clean, and you can control your temperature to a large extent. Avoid getting dehydrated or activities that cause you to tire quickly.

Should I Take Salt Tablets During Hot Weather?

Never take salt tablets.

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