At a glance
- Term
- PIH (post-inflammatory hyperpigmentation)
- Area
- Skin
- Measurable from a selfie
- Yes: flat dark marks where spots used to be
- Evidence
- Established
- Related
- Hyperpigmentation, PIE (post-inflammatory erythema), Acne, Azelaic acid
What PIH describes after a spot heals
A healed spot can leave colour behind, and that leftover pigment is the feature PIH describes. The term doesn't mean the original spot is still active or that the dark mark itself is a scar.
Post-acne marks fall under the broader term hyperpigmentation. If you're reading about acne, keep current spots separate from the flat marks left where earlier spots healed.
What a selfie can measure
Yes, PIH is measurable from a selfie as flat dark marks where spots used to be. A photo can record their visible pattern, but it can't establish that every dark patch has the same cause.
The free acne scan counts and maps visible spots from one photo. Its spot count isn't a separate PIH diagnosis or a measure of how long a mark will take to fade.
What helps dark marks fade
Think in months, rather than expecting a healed spot's colour to disappear at once. Sunscreen and an active ingredient aimed at pigment can help fading.
The American Academy of Dermatology's "How to fade dark spots in skin of color" supports sun protection and lists azelaic acid. Its guidance also advises addressing the cause of new marks, rather than treating leftover colour alone. If treatment doesn't give you the results you want, a dermatologist can help.
How to read the evidence and your result
Evidence: established. PIH names a recognised pigment change after inflammation, but that status doesn't validate every number produced from a photo.
Use a result to describe visible marks, rather than treating it as a fixed fact or predicting their fading time. If you're comparing terminology, the glossary also covers PIE (post-inflammatory erythema), a related label that doesn't confirm your own mark's cause.
Questions people ask
- What does PIH stand for?
- PIH stands for post-inflammatory hyperpigmentation, the pigment change that can remain after a spot heals. Here, it describes the flat brown or dark mark left behind.
- Is PIH a scar?
- The flat dark mark described as PIH is pigment, rather than a scar. Keep those terms separate when you're describing what a healed spot left behind.
- How long does PIH take to fade?
- Fading takes months, and sunscreen plus an active ingredient aimed at pigment can help it fade faster. A selfie can't give you a personal deadline.
Written from the measurements and ingredient facts on this site, then checked for the usual mistakes. Not medical advice.
Related pages
The closest pages in this section, picked by topic rather than by date.
- Understanding hyperpigmentation meaningUnderstand hyperpigmentation meaning, what darker patches show in a selfie, how sun protection helps, and why fading takes time.
- pie meaning: Post-inflammatory erythemaLearn the pie meaning in skincare, how pink or red marks differ from pigment, what a selfie can measure, and which steps can help.
- Skin collagen meaning: what it does and what helpsUnderstand collagen meaning, its role in skin firmness, why a selfie can't measure it, and how sunscreen and retinoids compare with drinks.
- Comedone meaning: Blackheads, whiteheads and photosComedone meaning explained: how blocked pores form blackheads and whiteheads, what a selfie can measure, and where acne treatments fit.
- Dark circles meaning: what under-eye darkness tells youDark circles meaning: understand pigment, visible blood vessels and hollow shadows, what a selfie can measure, and why lighting changes the
- Skin elastin meaning: why skin springs backUnderstand elastin meaning, how it helps skin snap back, why a selfie can't measure it, and why sunscreen matters more than promises of repa