Causes of black spots on the skin

Colour by itself is not enough for a diagnosis. A clinician also considers whether each area is flat or raised, new or longstanding, stable or changing, and associated with scale, pain, itching, or bleeding.

Flat marks often remain after acne, folliculitis, a bite, a burn, or friction because inflammation can stimulate extra pigment. Sun exposure may deepen existing pigment. A dark plug within a pore may be an open comedone, while a rough or scaly patch suggests a different process.

Distribution matters: marks following previous pimples point toward post-inflammatory change, whereas a single evolving lesion deserves direct inspection. On deeper skin tones, redness may look purple, brown, or grey rather than bright red.

Take a clear photograph beside a ruler and record the date, location, symptoms, and any recent rash or injury. Use gentle cleanser, avoid squeezing or scraping, and protect exposed areas from sunlight with shade, clothing, and a suitable broad-spectrum sunscreen.

Do not use acid mixtures, bleaching agents, or an unlabelled lightening cream. Treatment depends on the cause; fading pigment and treating an active infection or changing mole require different approaches.

Book a skin examination for a new dark spot that enlarges, changes shape or colour, looks different from your other marks, repeatedly crusts, or bleeds without a clear injury. A sore that does not heal also needs assessment.

Get urgent help when darkening accompanies severe pain, rapidly spreading redness, fever, blistering, skin peeling, or black tissue in an acutely unwell person. These features matter because they can signal significant inflammation, infection, or tissue injury.

Ask what features support the proposed diagnosis, whether the spot needs dermoscopy or a sample, and which treatment targets the cause rather than colour alone. Mention medicines, pregnancy, sun exposure, recent rashes, and family or personal history of skin cancer.