Post-inflammatory hyperpigmentation vs melasma: useful clues

Quick answer

PIH commonly appears where acne, irritation or injury happened. Melasma more often appears as recurring, usually symmetrical facial patches influenced by light, hormones and other factors. Both can coexist, and neither should be confirmed from an online checklist.

PIH leaves a map of prior inflammation

Post-inflammatory hyperpigmentation is an after-effect. Acne, eczema, picking, friction, burns and irritating products can all leave darker colour after the visible inflammation settles. The first useful question is therefore not “Which brightening serum?” but “What is still making new marks?” ^AAD

Melasma has a broader trigger pattern

Melasma commonly involves light exposure, hormonal influences and genetic susceptibility, and it can recur after improvement. Indian consensus recommendations treat photoprotection as a cornerstone while placing stronger topical combinations and oral options within clinician-directed care. ^{Indian consensus}

Similar colour does not mean identical biology

Reviews of facial hyperpigmentation in skin of colour cover PIH and melasma as distinct conditions with overlapping treatment categories but different diagnostic and risk considerations. ^{Clinical review} An ingredient can appear in research for both without becoming equally suitable for both—or for every person.

What we could not verify

Symmetry, colour and location are not enough to diagnose melasma or exclude another cause. Pigment depth, medication effects, hormonal context and a changing lesion require clinical history and examination.

Bottom line

Use the preceding event and distribution to ask a better question. Treat PIH as a signal to control inflammation; treat suspected melasma as a chronic pattern worth confirming before escalating actives.