Heat Rash

Overview  of heat rash

The steady progress of global warming is giving rise to numerous pathological disorders within the human body. The inhabitants of tropics, subtropics, humid and arid regions experience intense heat throughout the year. Hence they suffer the most. Among the numerous diseases arising from the growing heat worldwide, skin diseases are posing potential threats. The most severe form of these type of skin diseases is “heat rash”. According to the reports of the Center for Disease Control and Prevention, heat rashes affect 10-20% of people in the United States. They have also reported 128,885 deaths around the world in the year 2015 due to the diseases arising from intense heat. This is a global threat and requires the initiative of health organizations in all countries to address the existing sustainability concerns.

What is a heat rash?

Heat rash or “miliaria rubra” is a type of skin irritation due to excessive heat, which appears as clusters of elevated reddish eruptions or tiny fluid-filled blisters. Heat rashes are basically an allergic response of the body to extreme heat. They mainly appear on the chest, back, neck, arms, and elbows. They are more common in children, especially the new-borns. Heat rashes are usually not very critical or painful in nature and heal after a certain period of time. If heat rashes persist and continue spreading to other parts of the body, one should immediately consult with a dermatologist. In a few extreme cases, heat rashes slowly progress to skin cancer (melanoma).

What are the causes of heat rash?

The primary cause of heat rash is the sun. People who are exposed to direct rays of the sun are prone to different forms of heat rash. Heat rashes can also arise due to other sources of tremendous heat. Also, few people normally sweat more than others. The generalized causes of heat rash are compiled below-

• Excessive sweating
• Clogging of sweat glands due to the accumulation of wastes and dirt (impedes sweat to travel via sweat ducts to the skin surface)
• Over-activation of sweat glands
• Extremely hot weather with a complete absence of breeze or wind
• Direct exposure to UV light of the sun
• Heavy dressing (especially in humid weather)
• Non-habitual exposure to hot and dry climates
• Occupational hazards (Eg: Factory workers have direct exposure to the heat from blast furnace)
• The release of sweat to the immediate layer of skin (dermis) instead of the skin surface
• Impaired functioning of sweat ducts due to bacterial infection
• Covering the skin with an air-tight material (waterproof clothing)
• Insufficient cooling of the body (due to lack of bathing or unhygienic conditions)
• The extreme sensitivity of skin to an elevated temperature
• Decreased capability to respond to change in temperature (at old age)
• Existing illnesses like heart diseases, high blood pressure or fever
• Poor dietary habits
• Medications like sedatives, tranquilizers or steroids
• Skin ointments that block the sweat glands
• Low intake of fluids

What is the mechanism of heat rash formation?

In the tropical regions, a particular bacterial species called Staphylococcus epidermis exist on the skin surface normally and is usually benign. This bacteria releases a sticky fluid, which combines with excess perspiration and dead skin cells and blocks the sweat ducts. If one does not clean these wastes properly, they slowly accumulate and form heat rashes.

What are the symptoms of heat rash?

Heat rashes are confused with normal skin infections in many cases. For a proper diagnosis, the following symptoms of heat rash must be recognized-

• Clusters of elevated and coarse red lumps on the skin
• Tiny fluid-filled blisters
• Reddish streaks spreading from rashes
• Discharge of pus from blisters
• Extreme tenderness and touch sensitivity of skin
• Inflammation and itching of the skin surface
• Burning sensation when rashes are rubbed
• Pinprick sensation in the rash affected the region
• Occasional fever and body pains
• A headache, dizziness, and nausea

One should not scratch and rub heat rashes. The patients should not apply hard soaps at the sites of infection. This will prevent the rashes from getting worse.

Types of heat rash

According to the level of obstruction of the sweat glands, heat rashes can be classified into the following categories-

• Miliaria rubra: It is the most common form of heat rash and is also called “prickly” heat rash. It occurs due to clogging of sweat ducts at a deeper layer of the epidermis (external skin layer). It is characterized by very minute red papules or blisters which cause constant itching and pinprick sensation.
• Miliaria crystallina: This is mostly observed in new-borns and occurs due to obstruction of sweat ducts close to the epidermis. They typically appear in the form of vesicles (resemble clear sweat drops) and do not cause inflammation.
• Miliaria profunda: This is the rarest and most critical form of heat rash and is caused by clogging of sweat ducts in the dermis (middle layer of skin). These appear as big skin colored papules which worsen on sweating and are usually observed after the repeated occurrence of Miliaria rubra. This is associated with fever and heat exhaustion.
• Miliaria pustulosa: It is characterized by the formation of pustules due to bacterial infection. Acute inflammation occurs in this condition.

Depending on the size and texture, heat rashes can be of the following types-

• Raised rashes
• Flat rashes
• Lacy rashes
• Crusty rashes
• Pustules
• Welts
• Blotches

Diagnosis

Normally dermatologists can identify the type of heat rash by its appearance and symptoms. Radioallergosorbent tests (RAST) can be recommended for understanding the cause of the rash.

Treatment & Prevention

Usually, heat rashes don’t require treatment. These tend to disappear within a few days provided the area of skin is kept cool. One should refrain from using any type of oil or cream based product on the affected part of the skin. In case an infection develops at the site of rashes, the doctor will prescribe antibiotics. The most effective treatment is using cold compresses on the heat rash. These can be prevented by:

• Avoid high temperatures such as outdoor activities, warm baths, sauna – basically anything that can cause sweating.
• Refrain from engaging in intense physical workouts in places where it is hot and humid.
• Keep your body cool. Spend time indoors in cool and well-ventilated areas.
• Wear light natural fabrics such as cotton. Avoid synthetic fibers and/or tight-fitting clothes.
• Drink ample amount of water.

References