Treatment For Prickly Heat Rash and other Heat and Humidity Related Skin Conditions 

" Prickly heat rash, also referred to as Miliaria, is a common skin disease, typically brought on by overheating due to high heat and humidity. It can appear anywhere on the body.  This and other heat and humidity related problem such as Tropical Acne, Hypohidrosis syndrome and Cholinergic Urticaria are particularly common in tropical climates. While most of these conditions usually heal on their own,  it may cause a short circuit in the body’s heat-regulation ability, leading to illness. It is quite common in infants, small children and physically active people at work or that exercise ."   

What is Prickly Heat Rash

As outside temperatures increase, and body heat increases above normal levels, the body seeks to cool down.  When the sweat glands cannot keep up, as as humidity in the air decreases the ability of sweat to evaporate, the body heats even more. With sweat,  water levels and salt levels in the body decline, leading to dehydration.  Said another way, when outside temperature is higher than body temperature, the skin temperature will rise unless cooled by water or circulating air.

The result of inefficient cooling are heat related skin problems such as prickly heat.  Other conditions that are also heat related include cholinergic urticaria, tropical acne and hypohidrosis syndrome.

The causes of prickly heat include the following:

  • Heat
  • Humidity
  • Perspiration
  • Plugged sweat ducts, with bacteria from the staphylococcus family present on everyone’s skin
  • Plugged hair follicles, with bacteria from the staphylococcus family present on everyone’s skin

While it may seem like a minor problem, to have plugged sweat ducts and/or hair follicles, when they are plugged, they form tiny, clear, almost translucent watery bumps, that sting like the dickens when they burst. This is due to the salt in your sweat. Not only is sweat a skin irritant, it has the potential to cause skin rashes.

prickly heat rash
Prickly Heat Rash (Miliaria crystallina) Picture.  Note the superficial skin vesicles, with no noticeable skin inflammation.  Treatment is not required and the condition only lasts for a short period of time.
Source: Borden Institute, US Army

Prickly heat normally looks like a series of pointy, small bumps, located at the base of small hair follicles. You may see pink or red patches of skin initially. If your rash progresses, you may develop angry, raised red bumps, hives and skin welts and have an insanely irritating itch. Some people don’t experience the itch.

You may find prickly heat rash on various body parts, such as the:

  • Face
  • Neck
  • Abdomen
  • Groin
  • Back
  • Elbow folds
  • Under the breasts
  • Buttocks

Symptoms of Prickly Heat Rash

The first signal that you may have prickly heat is the red rash and small blisters in various locations on your body.  Quite often, the blisters will appear all at the same time. There are four categories of prickly heat rash, usually graded by what layer of skin they affect. Those categories are:

  • Miliaria crystalline: no rash, just tiny blisters, minor, if any symptoms.  Heals on its own in a short period of time.
  • Miliaria rubra: most common form, where blockage causes sweat to leak into deeper layers of the skin, producing red rash which are capped with  blisters (vesicles). Itching, prickly sensation, no sweating in those areas. Heat exhaustion is a possibility.  Treatment is required to keep the condition from becoming severe and then spreading to other parts of the body.
  • Miliaria profunda: this is a severe form of prickly heat rash that develops as the result of Miliaria rubra.  It spreads like wildfire, presenting with a severe burning sensations. Blockage is deep in sweat gland, which leaks into the deep layers of skin. Rash is skin colored; not red. Higher risk of heat exhaustion.
  • Miliaria pustulosa: pustules formed as a result of bacterial infection. Inflammation. Very high risk of heat exhaustion.  IT is always the result of some other type of skin inflammation that effects the sweat ducts.

    miliaria pustulosa
    Miliaria pustulosa is a type of prickly heat that results in discrete skin papules that are not associated with hair follicles. It occurs after other forms of dermatitis (skin inflammation) that impacts the sweat glands
    Source: Borden Institute, US Army

You may have signs and symptoms that include the following:

  • small red rash areas, or papules, which may itch and cause a prickling feeling
  • small red rash areas, which may not itch
  • larger areas of lesions that are flesh colored and may itch severely

Diagnosis of Prickly Heat Rash

Typically, prickly heat rash will go away on its own.  The best approach is to stay out of the heat and stay hydradated.  If you are in the heat, try and work in the shade and near a circulating fan or in circulating air.

However, if your rash doesn’t go away, it’s time to call your doctor. If you have the mild form of prickly heat rash, it will be evident on visual examination. The same holds true for the other forms of prickly heat rash; again, diagnosed on appearance and by your answers to questions about heat exposure.

If you have one of the more advanced forms of prickly heat rash, the doctor may want to take a skin culture, skin biopsy or exam skin scrapings to examine under a microscope. If the results are inconclusive, they may also get tests done for eczema, fungal infections, allergy reactions and bacterial infections.

If you have any of these following symptoms, go to the doctor immediately:

  • headaches
  • nausea
  • vomiting

Prickly Heat Rash Treatment

As mentioned, prickly heat rash will heal on its own.  To bring relief and to speed healing consider the following options:

  • Drink lots of water to assist your body in cooling down and remain hydrated
  • Lower the temperature in your home
  • Wash the area several times a day, with mild soap for sensitive skin, rinse and pat dry.
  • Try cool showers or baths
  • In areas where you have skin folds, tuck a clean piece of cotton to absorb sweat
  • Use a package of frozen corn or ice gel packs directly on the area(s), but do not leave them on any longer than 10 minutes on and then ten minutes off and repeat, or you run the risk of an ice burn
  • If you have more than a mild case of prickly heat rash, try hydrocortisone ointment found in your local pharmacy
  • If you have more than a mild case of prickly heat rash, you may get a prescription cream from the doctor, such as triamcinolone
  • If you have a bacterial infection, your doctor may give you antibiotics
  • You may also wish to try antihistamines (Claritin or Benadryl) to tackle the itching
  • Aloe vera
  • Honey paste
  • Lavender essential oil
  • Chamomile
  • Cool oatmeal baths
  • Cool Epsom salts baths
  • Try a homeopathic remedy that supports skin health such as Clear Skin.

Other Heat Related Skin Rashes

  • Hypohidrosis syndrome (tropical anhidrotic asthenia) occurs when the body stops sweating, or only sweats excessively in one area of the body such as the face.  Treatment involves rest and in a cool area over several weeks.  Recovery can take as long as 4 months.  Symptoms at the onset of Hypohidrosis syndrome is similar to prickly heat rash, and then becomes scaly.
  • Tropical Acne also occurs in hot climates where there is also high levels of humidity. It appears in individuals that had mild acne when teens, only to see tropical acne erupt later in life. It usually starts 3 to 6 months after moving to a tropical climate and is more prevalent in adults age 25 to 30.  Symptoms include skin lesions that are large, inflamed and pus filled.  Areas of the body include the upper thighs, buttocks, the entire torso (back and front), neck and arms.  The patient will feel sick.  Treatment involves moving to a cooler climate with lower levels of humidity.  Medications are available for treatment.
  • Cholinergic Urticaria is very common, particularly in younger adults. It is also triggered by high heat, particularly when exercising or in times  of stress. Individuals suffering from cholinergic urticaria will feel warm, followed by the appearance of skin wheals (1mm to 3mm in diameter). Other cholinergic urticaria symptoms include headache, nausea and pain in the abdomen). The wheals appear on the torso, but can appear in other areas of the body when the condition is chronic (severe).  Treatment involves removal from the heat, and no  exercise.  Antihistamines may be helpful.

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Skin Diseases Associated with Excessive heat, Humidity and Sunlight
Leonard Sperling, M.D.


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