Sweat rash blisters: what to know

Heat rash may look like tiny clear or whitish blisters, prickling bumps or red irritated patches after sweating. Friction, humid weather, tight clothing and covered skin can worsen it. Larger, painful or cloudy blisters are less typical of simple heat rash and may point to infection, contact irritation, a burn or another condition. Do not rely on a photograph or a single symptom to identify the cause.

Move to a cooler environment, remove damp clothing and wash gently with lukewarm water. Pat the skin dry and leave blisters intact; opening them increases irritation and can introduce infection. Wear loose breathable clothing and avoid rubbing, heavy creams, perfumed products and hot showers over the area. [Heat Rash](/conditions/heat-rash/) and [Skin Bumps](/symptoms/skin-bumps/) provide related explanations. If surrounding skin is dry, ask a professional whether [Emollient Therapy](/treatments/medical-dermatology/emollient-therapy/) is suitable. Do not apply [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/) to broken or infected-looking skin without advice.

Seek medical assessment if blisters are large, painful, spreading, filled with pus or blood, or surrounded by increasing warmth and redness. Prompt care is warranted with fever, weakness, severe tenderness or a rash affecting the eyes, mouth or genital area. Arrange a review if the eruption does not improve after cooling and gentle care or keeps coming back.

Ask whether the blisters fit heat rash, whether they should be covered, and which cleanser or treatment is appropriate. Tell the clinician when they appeared, where they are, whether they itch or hurt, and whether a new product, medicine, heat exposure or rubbing preceded them.