PIH (Post-Inflammatory Hyperpigmentation)
Definition
Post-inflammatory hyperpigmentation (PIH) is a type of hyperpigmentation that occurs as the skin heals from inflammation or injury — commonly from acne, eczema flare-ups, burns, cuts, or aggressive cosmetic procedures. During the healing process, excess melanin is deposited in the skin, leaving flat, darkened patches that range from pink to red, brown, or black depending on skin tone and the depth of melanin deposition. PIH affects all skin types but is more common and more persistent in medium to dark skin tones. While PIH is not scarring and will eventually fade on its own (over months to years), treatment can significantly accelerate resolution. Effective ingredients include vitamin C, niacinamide, alpha arbutin, azelaic acid, retinoids, and AHAs like glycolic acid. Consistent sunscreen use is absolutely critical, as UV exposure darkens and prolongs PIH. Avoiding picking or squeezing acne is the best prevention strategy.
Was this definition helpful?