# Post-Inflammatory Hyperpigmentation (PIH): A Clear Guide > Post-inflammatory hyperpigmentation is dark marks left after skin inflammation; treat the cause first. *Post-inflammatory hyperpigmentation (PIH) is the dark discoloration left at the site of healed skin inflammation — most commonly from acne, eczema, psoriasis, cuts, burns, or cosmetic procedures. It results from excess melanin deposited during and after the inflammatory process. PIH is more pronounced, darker, and slower to fade in deeper skin tones because inflammation deposits melanin into the dermis as well as the epidermis. The most important step is resolving the underlying inflammatory cause.* - Canonical: https://beautycomparison.com/pih-guide - Reviewed: 2026-06-20 - Publisher: Beauty Comparison (Beauty Comparison Editorial) — independent, brand-neutral ## Key takeaways - PIH is not a scar — it is a flat discoloration of excess melanin. It does not damage skin structure and will fade with proper treatment and time. - Treating the underlying cause (active acne, eczema, psoriasis) is the most important first step — continuing inflammation continuously creates new PIH. - In darker skin tones (Fitzpatrick IV–VI), PIH is darker, more pronounced, and slower to fade because melanin deposits into the dermis, not just the epidermis — deeper pigment requires longer treatment and sometimes professional procedures. - Azelaic acid is one of the best PIH treatments: it selectively inhibits overactive melanocytes, is safe in pregnancy, and is well-tolerated across all skin tones. - The number-one cause of PIH treatment failure is skipping daily SPF — UV exposure continuously re-stimulates the melanocytes at the PIH site, undoing any progress from brightening actives. - Popping pimples and aggressive picking dramatically worsen and deepen PIH by causing additional skin trauma and inflammation at the same site. ## What Is Post-Inflammatory Hyperpigmentation? Post-inflammatory [hyperpigmentation](/hyperpigmentation-guide) (PIH) is the flat, dark or discolored mark left at the site of healed skin inflammation. It is not a scar — there is no change to the skin's collagen structure or surface texture. PIH is purely a pigmentation change: excess melanin deposited at the site during and after the inflammatory process. PIH can result from virtually any type of skin inflammation or injury: - Acne — the most common cause in most skin types - [Eczema](/eczema-guide) (atopic dermatitis) - [Psoriasis](/psoriasis-skin-guide) - Contact dermatitis - Insect bites - Burns - Cuts and abrasions - Cosmetic procedures — chemical peels, laser resurfacing, dermabrasion, waxing - Ingrown hairs The resulting marks are typically tan, brown, dark brown, or reddish-brown in lighter skin tones, and dark brown to near-black or ashen gray in deeper skin tones, reflecting the deeper deposition of melanin in more melanin-rich skin. PIH is extremely common. Surveys show it affects over 65% of patients with acne globally, with rates rising substantially in patients with Fitzpatrick skin types IV–VI. In clinical surveys of patients of African and Asian descent presenting to dermatologists, PIH is frequently cited as the primary concern — more distressing than the underlying inflammatory condition that caused it. --- ## Why Darker Skin Tones Are Disproportionately Affected Understanding this disproportion requires a brief explanation of melanin biology: **Melanocyte density is similar across skin tones.** What differs is melanocyte *activity* and *distribution* of melanosomes (the organelles that package and transport melanin). In Fitzpatrick types V–VI, melanocytes are more reactive — they produce more melanin in response to inflammation, and the melanin produced is packaged in larger, individually distributed melanosomes that are more photostable (slow to degrade). **Epidermal vs. dermal PIH:** When inflammation is mild, melanin deposits primarily in the epidermis (the outer skin layers), producing a tan to brown mark that fades relatively predictably with topical treatment and time. When inflammation is significant or the skin type is darker, melanin-laden melanocytes and macrophages (melanophages) can deposit pigment into the dermis — the deeper layer. Dermal melanin appears gray, blue-gray, or grayish-brown and is much more difficult to treat topically because most topical brighteners do not penetrate deeply enough to target it effectively. This is why the same pimple can leave a barely visible mark in fair skin and a deep, long-lasting mark in brown or dark skin — and why treatment must be proportionate to the skin tone and the depth of PIH. --- ## Distinguishing PIH from Acne Scars PIH is frequently confused with acne scarring, but they are fundamentally different and require different management: | Feature | PIH | Acne Scar | |---|---|---| | Surface texture | Flat — no textural change | Depressed (atrophic) or raised (hypertrophic/keloid) | | Nature | Pigmentation only | Collagen disruption / tissue change | | Will it fade? | Yes, with treatment and time | No — scars are permanent; require procedures | | Fades with topicals? | Yes (epidermal) | Pigment component only; not the scar itself | | Responds to SPF? | Yes | Pigment component only | A patient can have both PIH and atrophic scarring from the same acne lesion — the flat dark marks respond to brightening treatment while the depressed pits do not. --- ## Step 1: Treat the Underlying Inflammatory Cause The most important and most frequently overlooked step in PIH management is controlling the source of inflammation. Every new acne papule, eczema flare, or scratched insect bite has the potential to create a new PIH mark. Until the inflammatory condition is controlled, the problem is being continuously renewed from the source. For PIH from acne: effective acne treatment (OTC adapalene, benzoyl peroxide, salicylic acid; prescription retinoids or antibiotics for moderate-severe cases) reduces the formation of new lesions and therefore prevents new PIH while existing marks fade. For PIH from eczema or psoriasis: working with a dermatologist to achieve better disease control — through topical corticosteroids, calcineurin inhibitors, biologics, or phototherapy as appropriate — is essential before the PIH can meaningfully resolve. --- ## The Treatment Approach ### Non-Negotiable: Daily SPF 50+ UV exposure stimulates melanocytes throughout the skin, but the melanocytes at a PIH site are already in a hyperactivated state — they are significantly more responsive to UV than surrounding normal skin. Even modest UV exposure darkens existing PIH marks and slows or reverses fading. Daily, year-round broad-spectrum SPF 50+ is the most important treatment step — not a supplement to brightening actives but the prerequisite that enables them. ### Evidence-Based Topical Brighteners for PIH **Azelaic acid (10–20%):** A dicarboxylic acid that selectively inhibits hyperactive melanocytes at PIH sites without significantly affecting normally active melanocytes. This selective action is particularly valuable for PIH treatment compared to hydroquinone, which inhibits melanin production broadly. Azelaic acid also has clinically proven anti-inflammatory properties, making it doubly useful when PIH is caused by ongoing acne or rosacea. It is safe in pregnancy (category B) and well tolerated across all Fitzpatrick skin types. The 20% prescription formulation provides faster results; 10% OTC is effective but takes longer. **Niacinamide (5–10%):** Inhibits the transfer of melanosomes from melanocytes to keratinocytes — a different mechanism to tyrosinase inhibitors. Multiple clinical trials confirm visible brightening over 8–12 weeks. Exceptionally well tolerated, no irritation risk, safe in pregnancy, and appropriate for all skin tones including Fitzpatrick VI. Can be applied morning and evening. **Retinoids (retinol OTC; tretinoin Rx):** Retinoids accelerate keratinocyte turnover, reducing the residence time of melanin-containing cells at the skin surface and accelerating their shedding. They also inhibit tyrosinase and reduce melanosome transfer. Prescription tretinoin (0.025–0.05%) produces faster results than OTC retinol for PIH, but the initial retinization/purge period (dryness, flaking, and occasionally increased breakouts) must be managed carefully in darker skin tones to avoid barrier disruption that could itself trigger more PIH. Start low, go slow: 0.025–0.1% retinol twice weekly, building frequency over 8–12 weeks. Use with nightly moisturizer. **Vitamin C (L-ascorbic acid, 15–20%):** Inhibits tyrosinase, neutralizes UV-generated reactive oxygen species, and provides antioxidant protection when applied in the morning before SPF. Most effective as a daytime antioxidant supporting the photoprotection strategy. Less potent as a standalone brightener than azelaic acid or hydroquinone, but a clinically useful addition to a complete regimen. **Tranexamic acid (topical 2–5%):** Disrupts keratinocyte-melanocyte signaling via the plasminogen-dependent pathway. Growing evidence supports use for PIH, particularly in combination products. Well tolerated. **Hydroquinone (2–4% OTC/Rx):** The most potent single topical brightener; inhibits tyrosinase and impairs melanosome synthesis. Effective but should be used in 3–4 month cycles to avoid exogenous ochronosis — a paradoxical permanent blue-black pigmentation that occurs with prolonged uninterrupted use, with higher risk in darker skin tones. Not recommended during pregnancy. For severe PIH in deeper skin tones, prescription 4% hydroquinone under dermatologist guidance offers the fastest topical results. **Kojic acid (1–4%) and alpha-arbutin (1–2%):** Both inhibit tyrosinase. Well-evidenced adjuncts to a complete regimen. Kojic acid can cause contact sensitization with long-term use; kojic dipalmitate formulations are more stable. Alpha-arbutin is generally better tolerated than kojic acid with comparable efficacy. --- ## Putting It Together: Sample Regimens ### OTC regimen for mild-moderate PIH (all skin tones) **Morning:** - Gentle cleanser - Vitamin C serum (15–20% L-ascorbic acid) - Niacinamide moisturizer (5–10%) - SPF 50+ (tinted mineral if darker skin tone) **Evening:** - Double cleanse - Azelaic acid (10% OTC) or niacinamide treatment - 2–4 nights per week: retinol (0.1–0.3%, building to 0.5%) - Moisturizer (ceramide-based) **Expected timeline:** First visible improvement 8–12 weeks; significant improvement 3–6 months for epidermal PIH. --- ### Prescription regimen for moderate-severe PIH (dermatologist supervised) **Morning:** - Gentle cleanser - Vitamin C serum - Moisturizer - SPF 50+ tinted mineral **Evening:** - Azelaic acid 20% (or hydroquinone 4% in treatment cycles) - Tretinoin 0.025–0.05% (2–3× weekly, building to nightly over 8 weeks) - Ceramide moisturizer **Expected timeline:** Visible improvement 4–8 weeks; significant improvement 3–4 months. Dermal PIH may take 12+ months. --- ## Professional Procedures for Resistant PIH For deep dermal PIH that is not responding to topicals after 3–6 months: **Chemical peels:** Superficial peels (glycolic acid 20–35%, salicylic acid 20–30%, or Jessner's formula) accelerate epidermal turnover. In Fitzpatrick types IV–VI, superficial peels are preferred — medium-depth peels carry high PIH risk in darker skin. Pre-conditioning with topical depigmenting agents for 4–6 weeks before peeling significantly reduces post-peel PIH risk. Series of 4–6 peels, 3–4 weeks apart. **Q-switched Nd:YAG 1064 nm laser:** The longest-wavelength Q-switched laser passes more deeply into the dermis with less epidermal absorption — the safest profile for targeting pigment in darker skin. Multiple sessions required. Risk of post-procedural PIH exists even with this wavelength; strict post-procedure SPF and topical preconditioning reduce but do not eliminate the risk. **Microneedling:** Increasing evidence for dermal PIH; may improve pigment that topicals cannot reach. Enhanced penetration of topical brighteners when applied immediately after microneedling. --- ## What Not to Do - **Pick, squeeze, or pop pimples.** The additional trauma directly deepens and expands PIH at the site — a brief moment of pressure creates a mark that takes months to fade. - **Aggressive physical exfoliation.** Harsh scrubs create micro-trauma and inflammation that can produce new PIH. - **Skip sunscreen.** The single most common reason PIH does not improve despite treatment is ongoing UV re-stimulation of hyperactive melanocytes. - **Overdo actives.** Irritating the skin with too many actives at once disrupts the barrier and can trigger inflammation that creates new PIH in sensitive skin — a particularly significant risk in darker skin tones. --- ## Frequently Misunderstood: PIH vs. Erythema Fresh acne marks in lighter skin tones are often pink or red initially before becoming brown. This early pink or red appearance is *post-inflammatory erythema* (PIE) — dilated blood vessels left by inflammation, not excess melanin. PIE requires a different approach (azelaic acid helps with both; niacinamide helps; vascular lasers like pulsed-dye laser are specifically effective for PIE). It is worth knowing which you have — a dermatologist can tell on examination. ## FAQ **Does PIH eventually fade on its own without treatment?** Very superficial epidermal PIH can fade without treatment over 6–24 months as the skin naturally turns over melanin-containing keratinocytes. However, 'fading on its own' requires strict sun avoidance — UV exposure continuously re-stimulates the hyperactivated melanocytes at the PIH site and prevents natural fading. In deeper skin tones where melanin deposits into the dermis, spontaneous resolution without treatment can take several years. Active treatment significantly shortens the timeline at every depth, and is the standard of care rather than watchful waiting. **Is PIH the same as a scar?** No — they are fundamentally different. PIH is a flat pigmentation change with no alteration to skin structure. Acne scars are permanent collagen disruptions producing depressed pits (atrophic scars: ice pick, rolling, boxcar), raised thickening (hypertrophic), or firm raised masses (keloids). PIH responds to brightening actives and SPF. Scars do not — the structural damage requires procedures (microneedling, fractional laser, subcision) to address. A patient can have both from the same acne lesion: the dark flat mark (PIH) fades; the depressed texture (scar) does not. **How long does PIH take to fade in dark skin tones?** In Fitzpatrick skin types IV–VI, epidermal PIH typically takes 6–12 months of consistent treatment and strict SPF to fade significantly. Dermal PIH — the gray-ashen marks from deep inflammation — can take 1–2 years or longer and may not respond fully to topicals alone, requiring professional procedures. The depth and time elapsed since the original inflammation are the main determinants of how long fading takes. Starting treatment and strict photoprotection as soon as the inflammation resolves gives the best outcome. **Can I use hydroquinone on dark skin for PIH?** Yes, with appropriate precautions. Hydroquinone 2–4% is used by dermatologists for PIH in all skin tones including Fitzpatrick V–VI. The key risks in darker skin — exogenous ochronosis from prolonged uninterrupted use — are managed by using treatment cycles (3–4 months on, 2 months off) rather than continuous use. Dermatologist supervision is recommended. If you are uncertain or if ochronosis is a concern, azelaic acid is a safer and effective alternative that selectively targets overactive melanocytes. **Will retinol help fade PIH marks from acne?** Yes — retinoids are one of the most effective ingredients for PIH. They accelerate cell turnover, reducing the time melanin-containing cells spend at the skin surface; inhibit tyrosinase; and reduce melanosome transfer to keratinocytes. In people with darker skin tones, retinoids must be introduced slowly (low concentration, 2–3× weekly) to avoid barrier disruption and retinoid dermatitis, which can itself cause PIH — the opposite of the intended effect. Prescription tretinoin 0.025–0.05% is faster-acting than OTC retinol; discuss this option with your dermatologist. ## When to see a professional Consult a board-certified dermatologist if: PIH is not improving after 3 months of consistent OTC treatment plus daily SPF; you have darker skin and want to consider prescription hydroquinone, chemical peels, or laser (professional oversight significantly reduces the risk of procedure-induced PIH); the dark marks are accompanied by textural changes or raised lesions that may represent scarring rather than PIH (different treatment required); you are unsure whether the pigmentation is PIH or another condition; PIH is accompanied by ongoing acne, eczema, or psoriasis that would benefit from prescription management; or the impact on wellbeing warrants a targeted treatment plan. ## Sources - Post-Inflammatory Hyperpigmentation: A Review of the Epidemiology, Clinical Features, and Treatment Options — PubMed Central / The Journal of Clinical and Aesthetic Dermatology (2010-07-01): https://pmc.ncbi.nlm.nih.gov/articles/PMC3318018/ - Management of Hyperpigmentation: Current Treatments and Emerging Therapies — PubMed Central / Dermatology and Therapy (2021-09-01): https://pmc.ncbi.nlm.nih.gov/articles/PMC8481706/ - Hyperpigmentation in skin of color: an overview — PubMed Central / Journal of Drugs in Dermatology (2012-11-01): https://pubmed.ncbi.nlm.nih.gov/23154046/ - Azelaic acid: Properties and mode of action — PubMed / Skin Pharmacology and Physiology (2014-01-01): https://pubmed.ncbi.nlm.nih.gov/24470271/ - Topical retinoids for pigmented skin — PubMed / Journal of the European Academy of Dermatology and Venereology (2006-09-01): https://pubmed.ncbi.nlm.nih.gov/16918625/ - How to Fade Dark Spots in Darker Skin Tones — American Academy of Dermatology (AAD): https://www.aad.org/public/everyday-care/skin-care-secrets/routine/fade-dark-spots _Health information, not medical advice._