ZocdocAnswersWhat is a heat rash?

Question

What is a heat rash?

I've be babysitting for my nephew (he's 1 and a half) and he keeps getting a red rash on his stomach when we're playing outside. Is this just a heat rash? What exactly causes this and what is it?

Answer

What you are describing sounds like your nephew has a heat rash. Heat rash (also known as prickly heat or miliaria) is known to commonly affect infants and children, especially in a hot, humid weather. Sweating is a self-regulating mechanism your body uses to maintain a constant temperature. In doing so, your body cools itself by sweating, and allowing that sweating or perspiration to evaporate. Heat rash arises when your sweat-producing glands become blocked and unable to function. As a result, the sweat can't get to the surface of the skin and becomes trapped underneath your skin to cause symptoms that range from superficial blisters to deep, red rash. When your nephew is playing outside in hot, humid weather, his sweat gland ducts can get blocked if excessive sweating occurs and isn't able to get rid of all the sweat he produces. Babies are especially susceptible to heat rash when they are exposed to warm weather, are overdressed, excessively bundled, or have a fever because their immature sweat glands are unable to function properly to allow their sweat to evaporate. In general, heat rash itself is not serious, but it may be a symptom of heat stroke (a life-threatening condition) that requires prompt medical care to prevent any serious complication such as organ failure. If your nephew has serious symptoms, including high fever; extreme thirst and dehydration; rapid heart rate; flushed appearance; shallow, rapid breathing; weakness; or any changes in mental status, you need to contact a doctor right away. Otherwise, I hope you find the information helpful. I would recommend a consultation with a pediatrician for more information.

This answer is for general informational purposes only and is not a substitute for professional medical advice.

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