Post-inflammatory hyperpigmentation, often called PIH, forms after acne when inflammation triggers the skin to produce excess melanin during the healing process. Melanin is the pigment responsible for skin color, and when the skin becomes inflamed from acne lesions such as papules, pustules, cysts, or nodules, pigment-producing cells known as melanocytes may become overstimulated. This can lead to flat dark marks that remain visible after the active breakout has healed.
Acne inflammation begins deep inside clogged hair follicles where excess sebum, dead skin cells, and inflammatory activity accumulate. As the immune system responds to the irritation, inflammatory chemicals are released into surrounding tissue. In some individuals, this process stimulates additional melanin production as part of the skin’s response to injury. The resulting discoloration may appear brown, tan, gray, or nearly black depending on skin tone and the depth of pigment within the skin.
Post-inflammatory hyperpigmentation is more common after moderate to severe inflammatory acne because deeper inflammation creates greater disruption within the skin. Picking, squeezing, or scratching pimples may further increase inflammation and raise the likelihood of dark marks forming. Repeated trauma can prolong the healing process and intensify pigment changes, especially when acne lesions are manipulated before they naturally resolve.
Although PIH is often confused with acne scarring, the two conditions are different. Post-inflammatory hyperpigmentation involves changes in skin color rather than permanent changes in skin texture. True acne scars develop when collagen and deeper structural tissue become damaged during healing. PIH may gradually fade over time, although the process can take several months or longer depending on skin tone, sun exposure, and the severity of inflammation.
Ultraviolet exposure can worsen post-inflammatory hyperpigmentation because sunlight may stimulate additional melanin production in already inflamed areas. This is one reason sunscreen is commonly recommended during acne treatment and recovery. Daily use of broad-spectrum sunscreen may help reduce darkening of acne marks and support a more even skin tone over time.
Several skincare ingredients are commonly used to help improve post-inflammatory hyperpigmentation while also addressing acne-prone skin. Retinoids may support skin cell turnover and gradually improve uneven pigmentation. Azelaic acid is often used because it may help reduce inflammation and target discoloration simultaneously. Niacinamide may support the skin barrier while helping improve visible redness and uneven tone. Chemical exfoliants such as salicylic acid or glycolic acid are also sometimes included to encourage gradual removal of pigmented surface cells, although excessive exfoliation may worsen irritation in sensitive skin.
Gentle skincare practices are important because an impaired skin barrier can increase inflammation and prolong healing. Overwashing, harsh scrubs, and combining too many active ingredients at once may irritate acne-prone skin and potentially worsen discoloration. Consistent moisturization and gradual introduction of active ingredients are often recommended to improve treatment tolerance.
Because post-inflammatory hyperpigmentation can persist even after acne breakouts improve, treatment usually requires patience and consistent skincare habits. Individuals with persistent discoloration or severe acne may benefit from evaluation by a dermatologist, who can help determine whether prescription treatments or professional procedures are appropriate based on skin type, pigmentation severity, and overall skin sensitivity.
