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Prickly Heat

Information about Prickly Heat

We Have to Know about the Prickly Heat

  • Miliaria (prickly heat), sometimes called as ‘sweat rash’ or a ‘heat rash, develops in some people when they sweat more than usual. The rash is not usually serious, but it can be itchy and uncomfortable often causing a stinging or prickling sensation on the skin.

Causes of Prickly Heat  

  • Miliaria is due to blockage of sweat ducts. There are thousands of sweat glands that lie just under the skin surface. These glands make sweat which travels down the sweat duct to the skin surface.
  • Excessive sweating can block up your sweat glands and trap sweat beneath your skin. This causes irritation and results in tiny pockets of inflammation which causes the rash

What blocks the sweat ducts?

  • Some people are more prone to miliaria than others. It seems that bacteria called Staphylococcus epidermidis may play a role. This bacterium lives harmlessly on the skin and miliaria is not an infection. However, this bacterium makes a sticky substance. This substance combined with excess sweat and dead skin cells may cause the blockage.
  • Anything else that blocks the sweat ducts can also cause miliaria. For example, if you place polythene tightly on your skin for 3-4 days, you are likely to develop a miliaria rash on the covered skin.
  • Miliaria can develop in anyone at any age. However, it is most common in children and babies as their immature sweat glands are more prone to get blocked. It is particularly common in newborn babies but soon clears up.
  • It usually occurs when you sweat more than usual, for example in a hot and humid climate.
  • People who are overweight are also more likely to get prickly heat
  • Miliaria can also occur in cooler climates when sweating is a problem. For example, people who lie on their back for long periods due to illness (for example, after having a stroke or a major operation) may get miliaria on their back.

Signs & symptoms of Prickly Heat

  • The symptoms of prickly heat tend to appear a few days after exposure to hot temperatures. But occasionally, symptoms do not appear for several weeks or months.

The rash can affect any part of your body, but most commonly appears on your:

  • Back, abdomen (tummy), neck, upper chest, groin, armpits, hands, feet.
  • If you have prickly heat, your symptoms are usually worse on the areas of your body that are covered by clothing. This is because your clothing can cause friction and make you sweat more often.

There are three types of miliaria:

Miliaria crystalline:

This is sometimes called miliaria sudamina. This is caused when the blockage of the sweat ducts is close to the surface of the skin. The rash is like tiny clear spots that appear in crops. They may look like beads of sweat. The spots tend to disappear within a few hours or days. This is the least itchy form of the condition, and there may not be any itch at all.

Miliaria rubra:

This is the common type and the one most people would identify as ‘prickly heat’. This is caused when the blockage of the sweat ducts occurs at a deeper part of the epidermis (the outer layer of skin). Crops of tiny red bumpy spots (tiny papules) develop. The spots are just a few millimeters in size and may look like tiny blisters. They occur most where there is friction with clothes.

They can be very Itchy – although it may be more of an intense prickling sensation. Some areas of skin become red.

The rash may occur within days in a hot climate. However, often the rash does not appear until weeks or months have passed in the hot climate. The rash tends to go within a few days if you get out of the hot environment and stop sweating.

On the affected areas of skin there is a reduced amount of sweat or no sweat at all. You may feel tired and become intolerant of heat. If you continue to sweat and the rash covers a large part of your body, then you have a risk of developing a high fever and/or heat exhaustion. This is because you are not able to sweat properly to get rid of body heat.

Miliaria profunda:

This is uncommon. It is caused when the blockage of the sweat ducts occurs at the level of the dermis (middle layer of skin). This typically occurs in people who live in a hot climate who have had repeated episodes of miliaria rubra. Bigger lumps develop on the skin when you sweat. These tend to be flesh-coloured as they are deeper than the miliaria rubra form.  There is little itch with this type of miliaria but there is a greater risk of developing a fever and heat exhaustion if much of the skin surface is affected.

Medical advice for Prickly Heat

  • If you feel generally unwell, you may be developing heat exhaustion. If this occurs, seek medical attention.

Self care for Prickly Heat

  • Avoid excessive heat and humidity where possible. Spend some time in the shade, or take a small fan outside with you. Being exposed to heat will only make you sweat more, and could make your rash worse.
  • Wear loose cotton clothing. Avoid wearing synthetic fibres, such as nylon and polyester, as they trap heat more easily than natural fibres.
  • Keep your skin cool. Taking a cool bath or shower will help to prevent sweating and soothe your skin. Take frequent cool showers to avoid developing the rash.

Treatment for Prickly Heat

Prickly heat is not a serious condition and rarely requires any specific treatment. Most rashes will disappear naturally after a few days. However, severe cases can last for several weeks. One or more of the following may help to treat miliaria and prevent further episodes from developing.

  • Calamine lotion can be used on sore and irritated skin. It will help cool and soothe your skin.
  • Hydrocortisone cream can treat a rash that feels particularly itchy and irritated. You can buy low-strength hydrocortisone cream. However, avoid using this cream on your face, and always follow the instructions.
  • Moisturizer creams (that contain anhydrous lanolin) help to prevent blockage of the sweat ducts. If you are prone to develop miliaria then it may be worth a try. Apply some to your skin before activities that make you sweat or on arrival to a hot climate.
Prickly Heat
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