Types of heat rash

A superficial type can appear as tiny, fragile clear or whitish blisters with little inflammation. A more familiar form causes small red bumps with prickling or itch, often where heat and clothing press against the skin. A deeper form develops farther below the surface and may produce firmer, flesh-coloured or red bumps after repeated heat exposure. The appearance can overlap, and other causes of skin bumps, skin rash, or skin redness can look similar.

Heat rash is also called miliaria, prickly heat, or sweat rash. The pattern alone does not identify the cause with certainty, particularly when lesions are painful, one-sided, scaly, or associated with discharge.

For any type, reduce heat and sweating, use loose clothing, wash gently, and let the area dry. Avoid scratching and heavy products that seal the skin. Superficial blisters should be left intact rather than rubbed. Red itchy bumps may benefit from a cool cloth and a bland moisturiser if the skin is dry; see Emollient Therapy. A clinician should guide any topical corticosteroid use, especially for deeper or folded-area inflammation; see Topical Corticosteroids.

Seek medical advice when bumps are deep and painful, persist despite cooling, recur often, or become warm, swollen, crusted, or filled with pus. Fever, rapidly spreading redness, or feeling unwell warrants prompt care because infection or another diagnosis may need treatment.

Ask which pattern best fits your skin, whether a medicine could be worsening sweating or irritation, and how to prevent episodes in your usual work, exercise, or climate.