Post-inflammatory hyperpigmentation (PIH) refers to any type of skin discoloration left behind after inflammation (including the inflammation associated with acne). Often referred to as acne marks or macules, this form of hyperpigmentation occurs when inflammation triggers melanin production during the healing process. As blemishes start to clear up, reddish or brown spots take their place.
Although PIH is often (misleadingly) grouped with acne scars, PIH is not acne scarring. Acne scars are permanent fixtures that result from irreparable damage to collagen and skin tissue, leaving behind thicker, raised lumps (called hypertrophic scars) or indents (appearing as keloid or atrophic scars). Acne marks, however, are simply changes in pigmentation. The discoloration is only temporary; these marks naturally fade over time.
If you're interested in speeding up this process (who isn't?) use a Vitamin C-based serum as well as skin-brightening products that include Kojic Acid. Our two biggest recommendations-- the two products we use ourselves-- are the Whitening Mask and the Vitamin C Serum.