Prickly Heat

"Prickly heat also called: miliaria, sweat rash and heat rash is a harmless type of skin rash. This rash occurs when the ducts connecting sweat glands with the surface of the skin get blocked & perspiration gets trapped under the skin. Prickly heat is usually seen when the climate is warm and or humid. It can also appear in other climates if a person is overdressed. People who are on bed rest & infants can also develop sweat rash. Miliaria is a benign condition and it's usually only the  itching which causes discomfort. In most cases, heat rash disappears on its own. Treatment is mainly directed towards the itching caused by it. Miliaria can be controlled by keeping the skin cool and dry and avoiding intense activity which causes excessive perspiration. "  

Symptoms and Diagnosis

Prickly heat occurs on any part of the body, however, it is usually seen in areas covered by clothes and those areas associated with increased sweating.

Commonly affected areas are the: face, neck, under the breasts, under the scrotum, back, chest, armpits, groin and stomach.

This rash appears as tiny spots, bumps or blisters. The blisters are usually associated with intense itching and a pins and needle sensation which can be uncomfortable. The affected area appears red due to inflammation. There are various types of prickly heat that are classified based on the level of obstruction of the sweat ducts and any associated bacterial infection.

Miliaria crystallina or miliaria sudamina, is a mild form of  this condition. The obstructed ducts of the sweat glands occur close to the surface of the skin. The affected person develops multiple tiny blisters that look more like pearls of sweat. There may be mild itching or no itching at all.

prickly heat
Prickly Heat Picture - Miliaria Crystallina
Source: U.S. Army; Dermatology Service, Walter Reed Army Medical Center

Miliaria rubra, is the most common form of this condition. The obstruction leads to seepage of sweat in to the surrounding tissue which causes inflammation. This leads to larger blister like rashes that are reddish. It is associated with symptoms like itching, pins and needles and lack of sweating in the affected part. If miliaria rubra affects larger part of the body, then mild fever may develop.

prickly heat
Picture Rubra

Miliaria profunda, is the most severe form of heat rash, but is uncommon.   In this form, there is complete obstruction of the sweat ducts in the deeper layer of skin, the dermis. This occurs in individuals who develop recurrent episodes of miliaria rubra.

Bigger flesh colored lumps develop on the skin. Itching is not common. But with this type of heat rash, there is an increased risk of developing fever and heat exhaustion as the body cannot dissipate heat through sweat. Miliaria pustulosa, occurs when the disease is associated with bacterial infection, due to continual scratching.

prickly heat
Picture Milliaria Profunda

Miliaria pustulosa occurs when  is associated with a bacterial infection. This form of miliaria is caused by constant scratching.

prickly heat
Picture Miliaria Pustulosa

heat rash
Picture Miliaria Pustulosa


Prickly heat rash appears on the skin when a person is in hot or humid  environments. Baby's are susceptible to prickly heat as their sweat glands are not as well developed. Obese individuals and those who sweat profusely are also more likely to get miliaria.

The condition occurs when the sweat ducts get blocked. The sweat which gets trapped causes inflammation, itching and tiny red bumps on the skin. The exact cause of this obstruction is not known.

It is believed that the bacteria Staphylococcus epidermidis may play a role. A sticky substance secreted by these bacteria along with dead skin cells may obstruct the sweat ducts causing this disease.

Medical Treatments

Common forms of this condition are harmless and will disappear on its own. Affected persons have intense itching and most often the treatment given  is to relieve itching.

Keeping the skin cool and dry prevents the development of this disease. One should consult a doctor if there is infection, if the rash persists for a long period of time and if it is associated with fever.

Various treatment options are:

  • Applying calamine lotion to the affected area keeping the skin cool and decreasing the amount of sweating.
  •  Menthol also has similar properties in keeping the skin cool.
  • Antiseptic soaps can be used which will reduce the number of bacteria on the skin which are believed to play a role in development of prickly heat.
  •  Moisturizer creams containing lanolin can be applied to skin which prevents blockage of sweat ducts.
  • Once the condition has developed, steroids creams can be applied which will reduce the inflammation.
  •  Antibiotics may be needed if there is superadded infection.

Natural Treatments

Various natural methods to treat prickly heat are:

  • Avoiding heat and humidity, an air conditioner or a fan can be used to avoid heat and humidity.
  • Keeping the skin cool and dry by staying in an air conditioned room and taking showers many times a day can keep the skin cool and dry. After showers, the skin should be allowed to air dry instead of toweling off. Prickly heat powders and antiperspirants can also keep the skin cool and dry.
  • Wearing loose cotton clothes can reduce the incidence of miliaria, Silk, nylon and polyester clothing should be avoided.
  • Avoiding creams and ointments as these can block the openings of the sweat ducts.
  • If you require something to help with itch, consider a homeopathic product that is taken orally such as Skin Dr.


  1. Merck
  3. National Health Service
  4. Mayo Clinic


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