Heat Rash

1 What is Heat Rash?

Heat rash is also known as prickly heat and miliaria and does not only occur in babies.

Heat rash can affect adults as well, especially during hot, humid weather.

Heat rash develops when blocked sweat ducts trap perspiration under the skin.

The symptoms of heat rash can range from superficial blisters  to deep, red lumps.

Some forms of heat rash feel prickly and intensely itchy. Severe form of hat rash may require medical attention.

However, the best way to relieve is by cooling the skin and prevention of sweating.

2 Symptoms

The symptoms of heat rash can range from superficial blisters to deep, red lumps.

Adults usually develop heat rash in skin folds and in places where clothing causes friction.

In infants, the rash is mainly found on the neck, shoulders and chest. The rash can also be present in the armpits, elbow creases and groin.

The types of miliaria are classified according to how deep the blocked sweat ducts are. There is a variation for each type.

The mildest form of heat rash is known as miliaria crystallina affects sweat glands in the top layer of the skin. This for is marked by clear, fluid-filled blisters and bumps that break easily.

Miliaria rubra (prickly heat) is a type that occurs deeper in the skin. Signs and symptoms include red bumps and itching or prickling in the affected area.

Occasionally the fluid filled sacs or vesicles of miliaria rubra become inflammed and pus-filled (pustular). This form is called miliaria pustulosa.

There is also a less common form of heat rash called miliaria profunda, which affects the dermis of the skin.

Retained sweat leaks out of the sweat gland into the skin, causing firm, flesh-colored lesions that resemble goose bumps.

3 Causes

Heat rash is caused by blocked or clogged sweat ducts. Instead of evaporating, sweat gets trapped in the skin causing inflammation and rash.

It has not yet been clarified why the sweat gland become clogged, but some factors seem to play a role, these include: immature sweat ducts that can easily rupture, trapping perspiration beneath the skin.

Heat rash is capable of developing in the first week of life, especially when the infant is warmed in an incubator, dressed too warmly or even has a fever.

Hot, humid weather can cause heat rash. Intense exercise, hard work or any other activity that causes heavy sweating can lead to heat rash.

Overheating in general can be a cause of heat rash as well. Prolonged body rest can be a cause of heat rash, especially for individuals with fevers.

4 Making a Diagnosis

No test are necessary in the diagnosis of heat rash, diagnosis is by appearance.

Setting up a doctor's appointment for heat rash is no necessary. However, severe heat rash  has to be treated with the assistance of a doctor, specifically a dermatologist to be sure it is not a different condition.

It is important to be prepared for the appointment in advance. Listing down the question about heat rash can help in this preparation.

Questions one might ask the doctor include the following

  • What could have caused this rash?
  • How can I treat it?
  • Do I need to limit physical activity until the rash clears?
  • How can I prevent it in the future?

5 Treatment

Treatment of heat rash may vary depending on its type.

For a mild heat rash, the only measure that can be taken is simply avoiding overheating.

Once the skin is cool, heat rash tends to clear quickly.

For more severe forms of heat rash, the use of ointments on the skin can help relieve discomfort and prevent any other complications.

Such topical treatments may include:

  • calacamine lotion to soothe itching,
  • anhydrous lanolin to prevent duct blockage
  • and prevents new lesion from forming.

Topical steroids can be utilized in the most serious cases.

6 Prevention

The following preventive measures can be put into place against heat rash: 

  • avoiding overdressing, especially during hot periods like summer. During this time it is advisable to wear soft, lightweight cotton clothing. In winter children should dress as warm as an adult.
  • Avoiding tight fitting clothes is another factor that can prevent heat rash. Tight fitting clothes can irritate the skin.
  • It is vital to stay in the shade or in an air-conditioner building or use of a fan to circulate the air. 

7 Lifestyle and Coping

The following tips may be very helpful in coping with heat rash and become more comfortable:

  • It is advisable to dress in loose, lightweight clothing during hot days.
  • Spending enough time in an air-conditioned building.
  • Bathing or taking a shower in cool water with a nondrying soap and afterward letting the skin air dry.
  • Calamine lotion or cool compresses can be used to calm itchy, irritated skin.
  • Avoiding the use of creams that contain petroleum or mineral oil, as these can block pores further.

8 Risks and Complications

There are various factors that can put you at risk of having heat rash. These factors include: 

  • Age: newborns are more susceptible to developing heat rash.
  • People living in tropical climate are at a higher risk of developing heat rash than individuals in temperate climates.
  • Anything that induces sweating is likely to lead to heat rash.
  • Physical activity that is done without the correct clothes to allow one's sweat to evaporate, can trigger heat rash.

Heat rash usually heals without any complications, but it can lead to infection which then causes inflamed and itchy pustules.