Prickly heat is a skin rash. It is caused by sweat under the skin. Heat rash usually occurs in hot, humid weather, conditions with which many Americans are intimately familiar. It is common in Australia in hot and humid areas. Heat rash typically appears a few days after exposure to an especially hot, humid environment. But it may not appear until weeks later.
Bacteria are the main cause of prickly heat. Bacteria form the plugs in the sweat glands. Excessive sweating can cause the sweat glands to become blocked with bacteria and dead skin cells which stops them from emptying properly. This causes the sweat to get trapped under the skin creating a spotty red, prickly rash. Prickly heat is often caused when well-meaning parents dress their baby too warmly, but it can happen to any baby in very hot weather. A baby should be dressed as lightly as an adult who is resting.
Symptoms may include:
- irritation (prickling)
- small blisters
- large, red areas on skin
- Clusters of blisters which are come and go during exposure to sunlight or humid, hot weather.
- Irritation to areas where perspiration is heavy.
Careful monitoring for symptoms of heat disease is important. If they appear, some decrease in the ambient temperature must be achieved by moving to the shade, taking a cool bath or shower, or turning up the air conditioner.
The rash itself may be treated with topical antipruritics. Preparations containing aloe, menthol, camphor, eucalyptus oil, and similar ingredients are available commercially.
If the rash is infected, antibiotics may also be needed. With treatment, prickly heat should disappear within 2 or 3 days.
Gently wash skin with soft gauze and lukewarm water and pat on a mixture of one part alcohol to three parts boiled water after cooled.
Dissolve Fuller's earth (Multani mitti) in water to make a thin paste. It should be smeared over the affected parts. When the paste dries, wash with cold water.
Antihistamine creams or medications will relieve the itch and natural oatmeal-based creams are very soothing. These are all available from most pharmacists.
Natural fibres such as cotton are less irritating than synthetic ones. Keeping the room temperature cool and also keeping the temperature of baths and showers cool helps too.