Post-Inflammatory Hyperpigmentation (PIH): The Complete Treatment Guide

To prevent and treat post-inflammatory hyperpigmentation (PIH) after acne or irritation, start with daily sunscreen (tinted if possible) and stop picking, then add azelaic acid once the skin is no longer raw or inflamed. Vitamin C and a retinoid such as tretinoin or adapalene can be added next. PIH is a color change, not true scarring, and it usually fades over months, faster with sun protection. If it has not improved after about 3 to 6 months, see a dermatologist.

PIH is reactive pigmentation, the skin responds to inflammation (acne, eczema, injury, laser) by producing extra melanin. Characteristic: flat, not raised, follows the shape of the original inflammation. Distinguishes from: melasma (hormone-triggered, symmetrical patches), sun spots (UV-caused, isolated spots), and true scarring (texture change, not just color).

PIH treatment priorities: 1) Tinted mineral SPF daily (prevents new PIH formation and protects existing). 2) Vitamin C morning (tyrosinase inhibition, brightening). 3) Azelaic acid 10% twice daily (anti-inflammation + anti-pigment). 4) Tretinoin nightly (cell turnover acceleration). Together these treat most mild to moderate PIH, though fading takes months, not weeks.

Tinted mineral SPF with iron oxides is critical for PIH because: visible light (not just UV) triggers pigmentation production. Iron oxides block visible light while protecting skin. For darker skin tones (Fitzpatrick III-VI), visible light is as much a trigger as UV. Untinted sunscreen protects against UV but allows visible light to worsen PIH. Tinted is a good idea for PIH, especially in medium to deep skin tones.

PIH in Fitzpatrick III-VI (medium-deep skin tones): often takes longer to resolve than in lighter skin, more prone to PIH from even minor inflammation, needs more careful product introduction to avoid irritation that triggers new PIH, especially benefits from tinted mineral SPF with iron oxides. Laser treatments must be used carefully, wrong lasers can worsen PIH in darker skin.

PIH fading varies a lot. Light pink or tan marks may improve in a couple of months, brown marks often take several months, and deep brown marks can take 6 months or more. Darker skin tones usually take longer. These are rough estimates, not studies, and without daily SPF the marks can last longer or return.

Stubborn PIH not responding to topicals after 4-6 months: in-office treatments. Chemical peels (TCA 10-20% in-office), Picosure laser for pigmentation, BBL/IPL for surface pigmentation, microneedling (accelerates PIH fading through remodeling). Combined with topicals for maximum effect.

PIH prevention: 1) Treat active acne aggressively (tretinoin, BHA, prescription if severe). 2) NEVER pick or squeeze acne (major PIH cause). 3) Use SPF daily (UV triggers new pigmentation). 4) Quickly treat any inflammation (eczema, rashes). 5) Avoid harsh physical exfoliation. Prevention is easier than treatment.