Post-Inflammatory Hyperpigmentation (rare)

Post-inflammatory hyperpigmentation (PIH) is a darkening of the skin that can occur after inflammation, especially in darker skin tones when AHAs are used improperly. This discoloration is due to increased melanin production and can be long-lasting.

Post-inflammatory hyperpigmentation (PIH) is a discoloration of the skin that occurs following inflammation or injury. While less common with certain alpha hydroxy acids (AHAs) compared to others or when used at lower concentrations, it can occur, especially in individuals with darker skin tones (Fitzpatrick skin types IV-VI). This hyperpigmentation results from an overproduction of melanin triggered by the inflammatory response. Improper use, such as excessive application frequency or extended contact time, can exacerbate the risk. The resulting dark patches or spots can vary in size and intensity and may persist for weeks, months, or even longer.