Those dark marks left behind after a pimple, a scratch or a patch of eczema are post-inflammatory hyperpigmentation (PIH) — one of the most common skin complaints in brown, Asian and Black skin. The reassuring part: PIH is not a scar, and it fades. The frustrating part: it fades slowly, and the wrong approach makes it worse — so it is worth knowing what actually helps, and what quietly sets you back.
What is post-inflammatory hyperpigmentation (PIH)?
PIH is a flat dark mark the skin leaves after inflammation — acne, eczema, a scratch, a burn or a harsh treatment. When skin is inflamed, pigment cells over-produce and leave a brown, grey or black patch where the spot was. It is the skin’s over-response to injury, and it is very common in skin of colour because darker skin pigments more readily.
Is PIH the same as acne scarring?
No — and the difference matters. PIH is flat pigment (a colour change) and it fades over time. A true scar is a texture change — a pit, a depression or a raised bump — and it does not fade on its own. Many people fear they have “acne scars” when they actually have PIH, which is far more treatable. If your marks are flat, they are pigment, not scars.
Why do I get dark marks after acne, especially in darker skin?
Because darker skin has more active pigment cells, so any inflammation — even a small pimple you did not pick — can leave a lasting mark. Picking or squeezing makes it worse by adding inflammation. Settling the underlying cause (like the acne) is the first step to stopping new marks forming.
PIH or melasma — how to tell?
They are often confused, and a doctor treats them a little differently. PIH follows an injury — you can usually point to the pimple, scratch or rash that came first, and the marks sit exactly where it was. Melasma is different: larger, symmetrical patches (often across the cheeks, forehead or upper lip) driven by hormones and sun rather than a single injury. They are eased along similar lines, but melasma is more stubborn and more sensitive to sun and hormones. If you are unsure which you have, see melasma in skin of colour and how melasma differs from sun damage.
Do dark marks from acne go away?
Yes — PIH usually fades on its own over 3 to 24 months, and gentle care with daily sun protection can speed it up. Sun exposure darkens the marks and slows fading, so sunscreen is essential. The newest, most superficial marks fade fastest.
What actually fades PIH — the actives that work
No single ingredient is magic. The marks fade fastest when a few gentle, evidence-based actives work together, each doing a different job — used at the right strength and pace, because anything that irritates skin of colour causes more inflammation, and more inflammation means more pigment. These are the actives a doctor reaches for:
- Niacinamide — calms inflammation and interrupts the hand-off of pigment into skin cells. Gentle, well tolerated in darker skin, and the reliable everyday base.
- Azelaic acid — evens tone by dialling down over-active pigment cells, and settles the acne that causes the marks in the first place — a useful two-in-one, and one of the safest options for brown, Asian and Black skin.
- Vitamin C — an antioxidant that brightens dull, marked skin and helps defend against the sun exposure that darkens PIH. A morning active, alongside sunscreen.
- Alpha-arbutin — a mild brightener that eases the look of existing marks without the harshness of stronger agents.
- Retinaldehyde (a gentle retinoid) — speeds up skin turnover so pigmented skin is replaced sooner. Powerful for renewal, but in darker skin it has to be introduced low and slow — too much, too soon irritates and backfires.
- Tranexamic acid — more often used for melasma; occasionally added, but the actives above do most of the heavy lifting for PIH.
Used sensibly, these ease the look of uneven tone over months. Used aggressively — high strengths, all at once, or harsh peels on top — they inflame skin of colour and make the pigment worse.
Why a doctor combines them (and starts slow)
One active cannot cover every job, so a doctor protects and brightens by day (vitamin C, niacinamide, alpha-arbutin, and — non-negotiable — a daily SPF) and renews by night (a gentle retinoid with azelaic acid). Just as important is the pace: in skin of colour the fastest route to worse pigment is doing too much too soon, so the routine is eased in — every third night, then alternate nights, then nightly — at the speed your skin tolerates. Matching the right actives and the right pace to your skin is the part a bottle off a shelf cannot do. It is what our evidence-based sun-protection guide is built around.
What makes PIH worse — what to avoid
- Picking or squeezing — every bit of extra inflammation adds a new mark.
- Harsh scrubs and strong peels — they promise fast fading but inflame darker skin and often deepen the pigment.
- Skipping sunscreen — sun darkens existing marks and undoes months of progress; daily SPF is the single most important step.
- Unsupervised long-term hydroquinone — a common “fade cream” ingredient that, used unsupervised for too long in darker skin, can cause a stubborn worsening of pigment (a condition called ochronosis). Powerful agents belong under a doctor’s eye.
- Chasing every active at once — more actives, higher strengths and faster is not better; it is the classic way PIH gets worse.
How to fade PIH safely in skin of colour
The safe approach in one line: settle the cause (the acne or eczema), protect from the sun every day, and introduce gentle, evidence-based actives slowly — never aggressive peels that risk more inflammation and more pigment. Track it over months so you can see it working. A doctor can match the actives and the pace to your skin. See how to tell if it is fading, melasma in skin of colour, and our photo-monitoring pathway.
This is cosmetic care for the look of uneven tone — not a medical treatment, and it cannot rule out skin cancer. Any mark that is changing, growing or unlike the others should be seen by a doctor.