High temperatures and muggy weather increase the incidence of heat rash because people increasingly sweat in these conditions.
Anything that causes eccrine duct blockages and prevents sweat from reaching the skin’s surface can cause heat rash.
FG Trade / Getty Images
First Time With Heat Rash: Why?
FG Trade / Getty Images
Heat rashis most common in hot, humid weather.
Heavy bedding or nightclothes can trap the sweat against your skin, causing a heat rash.
This photo contains content that some people may find graphic or disturbing.
Reproduced with permission from ©DermNetdermnetnz.org2023.
Reproduced with permission from DermNetdermnetnz.org2023.
What Causes Recurrent Heat Rash?
Heat rash can occur anywhere on the body where an eccrine sweat gland or duct is blocked or clogged.
You cannot get heat rash on your lips because lips do not have eccrine sweat glands.
Heat rash is caused explicitly by eccrine sweat glands or ducts getting clogged or blocked.
Anything that causes perpetual sweat gland blockage (occlusion) can cause recurrent heat rash.
Can You Get Heat Rash in Wintertime?
Slightly warm temperatures and conditions that moderately increase perspiration can trigger mild heat rash.
Summary
Heat rash (miliaria) is resulting from sweat trapped beneath the skin’s surface.
Heat rash is triggered by blocked sweat gland ducts that trap perspiration under the skin.
Obstruction of the eccrine sweat glands or ducts causes skin irritation and tiny bumps associated with heat rash.
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