Post-Inflammatory Hyperpigmentation (PIH)
Post-Inflammatory Hyperpigmentation (PIH) — a form of temporary skin darkening that appears after inflammation or injury, such as acne, eczema, or irritation, when the affected area produces excess melanin during healing. It shows up as flat brown, tan, or gray patches and is more common and often more persistent in medium to deep skin tones.
Key points
- PIH results from overproduction of melanin triggered by inflammation, not from active pigment sitting in living tissue.
- Common triggers include acne lesions, picking or squeezing, eczema, and cosmetic procedures that irritate the skin.
- Daily broad-spectrum sunscreen is central to management because ultraviolet exposure deepens and prolongs the marks.
- Ingredients such as vitamin C, niacinamide, azelaic acid, and retinoids are commonly studied for supporting a more even tone over time.
Frequently asked
How long does PIH take to fade?
It varies widely and can take several months to over a year to fade on its own, with sun protection generally helping it resolve faster.
Is PIH the same as a scar?
No; PIH is a change in pigment on otherwise intact skin, whereas a true scar involves a change in skin texture from altered collagen.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
