Heat bumps on skin: what to know

Heat rash commonly causes small itchy or prickly bumps where sweat collects, such as folds, the neck, chest, back, or areas covered by clothing. Folliculitis can centre on hairs and may become tender or contain pus. Keratosis pilaris tends to feel rough and recur on the upper arms or thighs, while milia are small, firm, pale cysts. Lichen planus can create a different persistent pattern. Colour, texture, duration, and symptoms around each bump help distinguish these possibilities.

Cool the skin gradually, shower with lukewarm water, and change damp clothing promptly. Keep folds dry, choose breathable fabrics, and cleanse gently without scrubbing or picking. Avoid thick fragranced products over a sweaty area. Do not puncture bumps or use strong acids, steroid mixtures, or antibiotics without guidance. If itching is troublesome, a clinician can advise whether an oral antihistamine treatment is suitable and safe with your other medicines.

Seek urgent care for breathing difficulty, swelling of the lips or tongue, severe pain with fever, rapidly spreading redness or swelling, or blistering and peeling. Arrange an appointment if bumps drain, bleed, enlarge, persist after cooling, or repeatedly return. A clinician should also examine a solitary firm or changing lesion rather than assuming it is heat rash.

Ask what features separate heat rash from folliculitis or a persistent lesion, and which cleanser or treatment will be least irritating for your skin.