What causes post-inflammatory hyperpigmentation?

The mark can follow acne, eczema, a cut, a burn, an insect bite, or an irritating skin procedure. It may look brown, grey-brown, or darker than the surrounding skin, and it can remain after the original redness, itch, or swelling has settled. Deeper inflammation may leave a longer-lasting colour change. People with more melanin in their skin may notice this response more readily, but it can occur in any skin tone. The mark itself is not an infection, although the inflammation that preceded it may need treatment.

Treat the active cause and avoid picking, scratching, friction, and untested lightening products. Use broad-spectrum sun protection and reapply it as directed, because ultraviolet exposure can darken the area and increase contrast. Keep a simple record of new products, flare-ups, and colour changes. A dermatologist may discuss [Skin Brightening Treatment](/treatments/aesthetic-procedures/skin-brightening-treatment/), a chemical peel, or a laser option after the skin is calm; treatment choice depends on the depth and cause of the pigment.

Arrange an assessment if pigmentation appears without a preceding rash or injury, changes quickly, becomes raised or painful, bleeds, or affects the eyes or mouth. Seek care for ongoing acne, eczema, or irritation rather than treating the mark alone. A clinician can check whether the pattern fits [Post-Inflammatory Hyperpigmentation](/conditions/post-inflammatory-hyperpigmentation/) or another cause of [Dark Patches On Skin](/symptoms/dark-patches-on-skin/).

What triggered the pigment change, and is that condition still active? Is the colour superficial or deeper? Which sunscreen and treatment are suitable for my skin tone, and what irritation should make me stop?