A type of heat rash called Miliaria Rubra, which can also be known as prickly heat, causes small red bumps that may itch or be irritating. The sweat glands become blocked and cannot work properly, leading to skin irritation. Friction can exacerbate the rash, so body parts that touch or rub together such as between the legs or under the arms are most likely to be affected.
Most cases of miliaria rubra occur in warmer or humid climates, and are most likely to happen to people who are not used to this type of environment. Excessive sweating or over-bundling can make you more vulnerable. Anyone can get heat rash, but Asian people are slightly less likely to get this form of the rash.
Very young children who are overdressed are susceptible to heat rash, because caregivers are often concerned that they be kept warm enough.
The most obvious sign of heat rash are the small, red bumps that it causes. These can appear on any area of the body, but most commonly on areas with friction, including body folds. Most people who suffer from heat rash do not get the bumps on their faces, hands or soles of the feet.
The bumps may become itchy or may sting or feel prickly, and this sensation becomes worse if you become overheated again.
Heat rash can also cause you to become easily tired and have difficulties coping with the heat. You may also stop sweating or sweat less, especially in the affected areas.
The best treatment for heat rash is to get to a cool, comfortable environment. Once you’re not overheated and your sweat glands are no longer blocked, your skin will recover. Bathing or showering in cool water with a non-drying soap can help to soothe the skin and clear the rash.
Calamine lotion or another ointment intended for mild rash can help resolve the itching and prickly feeling. Make sure you don’t choose a lotion or ointment that contains petroleum, as this can further block the sweat glands and make the rash worse.
For very severe cases of heat rash, your doctor may prescribe a topical steroid.