Both PIH and PIE are responses to inflammation and irritation. PIH is a melanin response that leaves a dark mark on the skin. It can happen when a pimple is irritated by picking or squeezing. It can be the result of an injury to the skin from a scratch, heat, UV exposure, or chemical burn. PIH tends to be more common in darker skin tones because of the abundance of melanin.
PIE appears as pink or red marks on the surface of the skin. It’s a vascular response to inflammation or irritation. Capillaries just under the surface of the skin are stimulated by the inflammation creating a surge of blood in the area as a healing mechanism. Like PIH, it’s caused by picking at pimples, UV exposure, chemicals, injury, or irritation. PIE is more common in lighter skin tones. The lighter the skin tone, the longer the marks will remain.
Neither PIH nor PIE is permanent but, in both cases, fading them takes time, patience, and strategy.