Heat rash with black dots: what to check

A dot can look dark after sweat, dried discharge or a tiny scab collects on an irritated bump. Hair follicles may also appear darker when blocked, and rubbing or scratching can leave a crust. These possibilities differ from pigment changes that remain after inflammation. Heat-related prickling and bumps can occur at the same time, but the dots themselves do not establish the diagnosis. Look for associated pain, warmth, pus, bleeding, scale or change in size. A page about [Skin Bumps](/symptoms/skin-bumps/) may help you describe the surrounding texture.

Cool the skin and reduce sweat, friction and pressure. Wash gently, pat dry, and leave any crust intact rather than scraping or squeezing it. Avoid picking, harsh exfoliation, fragranced products and heavy occlusive ointments over an uncertain eruption. Wear clean, loose clothing and change it after sweating. If dryness remains, [Emollient Therapy](/treatments/medical-dermatology/emollient-therapy/) may be relevant. Do not self-treat unexplained dark spots with a steroid; a clinician can decide whether [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/) have a role.

Have the area assessed if the dots are new and persistent, multiply, bleed, form a firm changing spot, or sit within a painful or draining rash. Prompt care is appropriate for spreading redness, increasing warmth, fever, significant swelling, severe pain, facial swelling or breathing difficulty. Photographing the area in consistent light can help show change, but it does not replace examination.

Ask whether the dots fit [Heat Rash](/conditions/heat-rash/) with surface crusting or whether a follicle, infection, mole or pigment change should be considered. Mention whether they appeared after scratching, shaving, a new product, sweating or friction, and report any discharge, bleeding, pain or change in shape.