Post-Inflammatory Hyperpigmentation (PIH): How to Improve the Look of Dark Marks from Acne

Editorial note: This article is for general skincare education only. It does not diagnose, treat, or replace advice from a dermatologist, OB-GYN, or other licensed clinician. If you are pregnant, breastfeeding, using prescription medications, or dealing with persistent or severe symptoms, confirm product and ingredient choices with your healthcare provider.

The pimple is gone but the dark mark remains. Sometimes for months. Sometimes for over a year. If you’ve ever wondered why your skin “scars” so easily from breakouts when other people’s just clears — you may not actually be dealing with scars at all. You’re dealing with post-inflammatory hyperpigmentation, and unlike true scars, it does fade.

What PIH actually is

Post-inflammatory hyperpigmentation (PIH) is exactly what it sounds like: excess pigment that forms in skin after inflammation. When your skin gets inflamed — from acne, a bug bite, a cut, a burn, eczema, or any other source — your melanocytes (the cells that produce pigment) respond by ramping up melanin production in the affected area. Sometimes this is mild and fades quickly. Sometimes the melanocytes overproduce dramatically, leaving a brown or dark mark long after the original inflammation has resolved.

The medical name is post-inflammatory hyperpigmentation, but you’ll see it called:

• Post-acne marks
• Dark spots from pimples
• Acne pigmentation
• Hyperpigmentation scars (technically incorrect — they’re not scars)
• PIH (the medical abbreviation)

PIH vs. true acne scars — important distinction

Many people use “acne scars” to describe what’s actually PIH. The two are fundamentally different:

• PIH — flat, discolored (brown, red, or purple), located where a pimple was. NOT a structural change to the skin. Fades over time, usually fully resolves with treatment within 4-12 months.
• True acne scars — textural changes in the skin. Either depressed (icepick scars, rolling scars, boxcar scars) or raised (hypertrophic scars, keloids). Result from collagen damage during severe acne. Don’t fade on their own, require treatments like microneedling, lasers, or fillers to improve.

You can have both PIH and true scars in the same area. The flat brown marks are PIH; the dents or raised areas underneath are scarring.

This article is about PIH. The good news: PIH is far more responsive to topical treatment than true scarring.

Why some people get PIH worse than others

Several factors influence PIH severity and persistence:

Skin tone. PIH is dramatically more common and more persistent in people with medium-to-dark skin (Fitzpatrick skin types III-VI). The melanocytes in darker skin are more “reactive” — they ramp up pigment production more aggressively in response to inflammation. This is why women with brown or black skin often deal with PIH that lasts a year or more, while women with very fair skin might see post-acne marks fade in weeks.

Severity of original inflammation. A small whitehead that resolves quickly usually leaves minimal PIH. A deep cystic pimple that lingered for weeks before clearing often leaves significant PIH.

Picking and squeezing. The single biggest controllable factor. Picking at acne extends inflammation, deepens the wound, and dramatically increases PIH severity. Hands off, always — even when impossible.

UV exposure during healing. Sunlight stimulates melanocytes in already-pigmented areas, making PIH darker and more persistent. Daily sunscreen during acne healing is critical.

Genetic predisposition. Some people simply produce more melanin in response to inflammation than others, independent of skin tone.

How PIH fades on its own (and how long it takes)

Even without any treatment, PIH does fade. The melanin produced during inflammation is gradually broken down by your skin’s natural processes and cycled out through normal cell turnover.

Realistic timelines without intervention:

• Light skin (Fitzpatrick I-II): 3-6 months for most PIH to resolve
• Medium skin (Fitzpatrick III-IV): 6-12 months
• Darker skin (Fitzpatrick V-VI): 12-24 months or longer; some PIH may persist indefinitely without treatment

These timelines assume no new inflammation in the same area. If you keep getting acne in the same spots, the PIH layer compounds over time.

With topical treatment, these timelines can be cut roughly in half. With professional treatments combined with topicals, further accelerated.

The ingredients that actually fade PIH

Vitamin C (L-ascorbic acid 10-20%)

Excellent for PIH. Inhibits tyrosinase (the enzyme that makes melanin), provides antioxidant protection against new pigment formation, and brightens overall tone. Apply every morning. Visible improvement in PIH typically begins at 8-12 weeks of consistent use.

Reliable picks: Maelove Glow Maker ($30), Skinceuticals C E Ferulic ($182), Timeless 20% Vitamin C ($30).

Niacinamide (5-10%)

Reduces the transfer of melanin from melanocytes to surrounding skin cells. Has anti-inflammatory effects that prevent new PIH from forming after each breakout. Pairs well with vitamin C. Apply morning, evening, or both.

Reliable picks: The Ordinary Niacinamide 10% + Zinc 1% ($8), Glow Recipe Niacinamide Dew Drops ($35), Paula’s Choice 10% Niacinamide Booster ($44).

Azelaic acid (10-20%)

One of the best PIH treatments. Inhibits tyrosinase, has anti-inflammatory effects, AND prevents future acne. The triple action makes it ideal for active acne sufferers dealing with PIH.

Reliable picks: The Ordinary Azelaic Acid Suspension 10% ($8), Paula’s Choice 10% Azelaic Acid Booster ($40), prescription Finacea 15%.

Retinoids (retinol, retinaldehyde, adapalene, tretinoin)

Accelerate cell turnover, gradually fading pigmented cells as they cycle to the surface and shed. Adapalene (Differin Gel, $15) is particularly useful because it treats both PIH AND new acne formation. Apply nightly after the introduction protocol (see “How to start retinol” articles).

Alpha arbutin (2%)

Plant-derived tyrosinase inhibitor. Gentler than hydroquinone but effective for PIH. Works gradually over 3-6 months. Often included in K-beauty brightening formulations.

Reliable picks: The Ordinary Alpha Arbutin 2% + HA ($10), Naturium Alpha Arbutin Treatment 2% ($16).

Tranexamic acid (3-5%)

Originally developed as an oral medication for excessive bleeding, tranexamic acid has emerged as an effective topical treatment for hyperpigmentation including PIH. Works through multiple anti-pigmentation mechanisms.

Reliable picks: The Inkey List Tranexamic Acid Serum ($16), SkinCeuticals Discoloration Defense ($110).

Hydroquinone 2% (over-the-counter) or 4% (prescription)

The most aggressive topical for PIH. Directly inhibits tyrosinase and disrupts melanocyte function. Works faster than other options but with more side effect potential (irritation, ochronosis with prolonged use). Best used short-term (3-4 months) under dermatologist guidance.

Glycolic acid (5-10%)

Exfoliating alpha-hydroxy acid that accelerates removal of pigmented surface cells. Effective alone but more powerful in combination with the actives above.

The complete PIH-fading routine

Most effective approach combines multiple actives applied at different times of day:

Morning

1. Gentle cleanser
2. Vitamin C serum (15-20% L-ascorbic acid) — patted into clean dry skin
3. Niacinamide serum (5-10%) — can be layered with vitamin C or used in combination products
4. Moisturizer — ceramide-based
5. Sunscreen (broad-spectrum SPF 30+) — especially important. Without daily sunscreen, PIH treatment is fighting a losing battle. Tinted formulations are ideal because they also block visible light, which contributes to pigmentation.

Evening (alternating treatments)

The most effective approach uses different actives on different nights:

Nights 1 & 3 of the week:

1. Gentle cleanser
2. Wait 15-30 minutes until skin is fully dry
3. Retinoid (Differin Gel 0.1% or prescription tretinoin)
4. Wait 10 minutes
5. Moisturizer

Nights 2, 4, 5:

1. Gentle cleanser
2. Azelaic acid 10-15%
3. Moisturizer

Nights 6 & 7: Recovery — just cleanser and moisturizer. Even powerful routines benefit from rest days.

Sun protection is the foundation

If you only do one thing for PIH, do this: daily, generous, mineral-based sunscreen with iron oxides for visible light protection. Reapply every 2 hours if outside.

Without strict sun protection:

• Existing PIH gets darker
• New PIH forms more easily
• All other treatments produce only partial results

Tinted mineral sunscreens are particularly important: EltaMD UV Elements Tinted, Colorescience Total Protection Face Shield, Tower 28 SunnyDays Tinted. The iron oxides in tints block the visible light wavelengths that drive pigmentation — UV protection alone isn’t enough for PIH-prone skin.

What to expect — realistic timeline

Weeks 1-4: Mostly nothing visible. You may notice slight skin texture improvement or brightening of overall tone. The PIH marks themselves haven’t changed much yet.

Weeks 5-8: Subtle fading begins. The most recent (and lightest) PIH marks start lightening visibly. Older or darker marks show minimal change.

Months 3-4: Substantial fading of light-to-moderate PIH. Skin tone becomes noticeably more even. Darker, older marks have begun fading but are still visible.

Months 5-8: Most PIH significantly faded. Skin tone substantially evened. Very dark or deep PIH may still be visible but much lighter.

Months 9-12: Continued improvement. Combined topicals plus consistent sun protection produces near-complete resolution of most PIH for most users.

If you’re 6 months in and seeing minimal change, evaluate:

• Are you using sunscreen every day (and reapplying)?
• Are you using enough product (full nickel-sized for face, applied generously)?
• Are you applying consistently (not just when you remember)?
• Are you still picking at new breakouts?
• Is your skin tone Fitzpatrick V-VI? (May need professional treatment + topicals combined.)

What to avoid (the PIH trap list)

• Picking, popping, squeezing. The single biggest cause of severe and persistent PIH. Every time you pick, you extend inflammation and deepen the pigment response.
• Over-exfoliating. Some people respond to PIH by aggressive scrubbing, which creates MORE inflammation and MORE PIH. Gentle approaches win.
• Combining multiple aggressive actives at the same time. Retinoid + azelaic acid + vitamin C + glycolic acid all on the same night = inflammation = more PIH. Use different actives on different nights.
• Skipping sunscreen. Critical. Without daily SPF, you’re constantly creating new PIH faster than topicals can fade old PIH.
• Stopping treatment too early. Most PIH treatments need 3-6 months minimum before assessing results. Quitting at 6-8 weeks because you’re not seeing dramatic change wastes the work you’ve already done.
• “Spot treating” PIH with strong actives. Applying hydroquinone or strong acids only on the dark spots can create the opposite problem — lightening AROUND the spot, leaving an outline. Apply treatments evenly to the affected area, not just on the spot.
• Lemon juice, baking soda, or other “DIY” treatments. Lemon juice on skin can cause phototoxic burns. Baking soda is highly alkaline and barrier-damaging. Skip the home remedies.

When to see a dermatologist

• PIH that hasn’t responded to 6 months of consistent topical treatment
• Severe PIH that’s significantly affecting quality of life
• Interest in prescription-level options (hydroquinone, tretinoin, combination creams like Tri-Luma)
• Interest in professional treatments (chemical peels, microneedling, lasers) that can accelerate results
• If you have true textural acne scarring along with PIH — different treatment approach needed
• If you’re getting new acne in the same areas repeatedly, suggesting underlying acne needs more aggressive management
• Darker skin tones (Fitzpatrick V-VI) with persistent PIH that hasn’t responded to over-the-counter approaches — board-certified dermatologists who specialize in skin of color often have specific protocols that work better for these skin types

Professional treatments for stubborn PIH

If topicals haven’t fully resolved your PIH after 6-12 months, professional options can produce results topicals can’t:

• Chemical peels (glycolic acid, salicylic acid, TCA, mandelic acid) — accelerated exfoliation. Multiple sessions typically needed. Cost: $100-300 per session.
• Microneedling — stimulates collagen and improves delivery of topical actives applied immediately after. Particularly useful for combined PIH and textural scarring. Cost: $200-500 per session.
• Q-switched lasers — target melanin pigment specifically. Effective but with higher risk in darker skin tones. Cost: $250-500 per session.
• PicoSure lasers — newer technology, often better tolerated in skin of color. Cost: $400-800 per session.
• IPL (intense pulsed light) — broader-spectrum light, effective for PIH in lighter skin tones. NOT recommended for darker skin (risk of paradoxical hyperpigmentation). Cost: $200-400 per session.

For darker skin tones specifically, find a dermatologist with experience in skin of color. The wrong professional treatment in darker skin can paradoxically worsen pigmentation.

Frequently asked questions

How do I tell PIH apart from true acne scars?

PIH is flat — you can run your finger over it and feel no texture difference. True scars are textural — depressed (most common) or raised. PIH fades over time (months to years); true scars don’t fade without treatment.

Can I use multiple PIH treatments at once?

Yes, but space them out. Vitamin C and niacinamide in the morning, retinoid one night and azelaic acid another, etc. Don’t layer 4 aggressive actives at once — you’ll trigger more inflammation and create new PIH.

Will my PIH come back if I stop treatment?

The faded PIH won’t return, but you’ll lose the risk reduction benefit of your routine — meaning new breakouts will leave new PIH again. Most people maintain a simpler maintenance routine (sunscreen + vitamin C + occasional retinoid) long-term.

Can I get PIH from things other than acne?

Yes. Bug bites, ingrown hairs, eczema flares, contact dermatitis, cuts and scrapes — anything that triggers skin inflammation can produce PIH. The treatment is the same.

Is PIH more common during pregnancy?

Yes. Pregnancy hormones increase overall melanin production, making PIH form more easily and persist longer. Many women see significant fading of pregnancy-era PIH in the year postpartum.

I’m Black/dark-skinned — do these recommendations apply to me?

The principles do, but the timeline and intensity may differ. Darker skin is more prone to PIH and may need longer treatment periods. Be more cautious with strong actives — what’s tolerable on lighter skin may cause irritation (and more PIH) on darker. Sun protection and gentle, consistent topicals are even more important. Consider seeing a dermatologist with skin-of-color expertise for personalized recommendations.

Will retinol make my PIH worse before it gets better?

The “purge” period of retinol introduction can cause new breakouts, which can create new PIH. This is why slow introduction protocols matter. After the adjustment period (8-12 weeks), retinol becomes a powerful tool for fading existing PIH while preventing new acne (and thus new PIH).

The bottom line

PIH — the dark marks left behind after pimples heal — is not a scar. It’s a temporary pigmentation response that fades with time and accelerates dramatically with the right topical treatment.

The core routine for PIH:

• Daily mineral sunscreen with iron oxides (critical)
• Vitamin C serum every morning
• Niacinamide serum daily
• Azelaic acid 10-15% several nights per week
• Retinoid (Differin Gel or tretinoin) several nights per week
• Gentle ceramide moisturizer twice daily

Stick with this routine for 3-6 months and most PIH visibly fades. Stick with it for 12 months and most PIH substantially resolves. The patience requirement is real, but so is the result.

And the risk reduction side: don’t pick at breakouts (even though it’s hard), use sunscreen religiously, manage active acne aggressively so new PIH doesn’t form. The PIH you don’t create in the first place is the PIH you don’t have to fade.