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

Post-inflammatory hyperpigmentation (PIH) is dark marks left on skin after acne, eczema, or other inflammation. Treatment: Vitamin C (tyrosinase inhibition), azelaic acid 10% (anti-inflammatory + anti-pigment), tretinoin (cell turnover), mineral SPF (prevention). Results visible in 4-8 weeks for mild, 8-16 weeks for moderate, 4-6 months for severe. PIH in darker skin tones takes longer but responds to the same treatments. NOT true scarring — can be fully resolved.

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). This four-product stack treats most mild-moderate PIH in 4-12 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 essential for PIH.

PIH in Fitzpatrick III-VI (medium-deep skin tones): takes longer to resolve (4-8 weeks more than lighter skin), more prone to PIH from even minor inflammation, requires more careful product introduction to avoid triggering 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 treatment timelines by severity: Mild PIH (light pink/tan marks) — 4-8 weeks. Moderate PIH (brown marks) — 8-16 weeks. Severe PIH (deep brown, scarring-like appearance) — 4-6 months. Darker skin tones — add 4-8 weeks to each timeline. Without daily SPF, these timelines extend significantly. Compliance is critical.

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). These options cost $300-1,500 per session. 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 dramatically easier than treatment.