Written by Dr Gerard Ee | Medically reviewed by Dr Gerard Ee | Expert opinion by Dr Gerard Ee
Dr Gerard Ee is an aesthetic doctor and the founder and medical director of The Clifford Clinic, which he established 14 years ago. He has treated acne scars for 16 years and more than 2,000 acne-scar patients, and is one of Singapore’s longest-standing users of the Infini RF microneedling system (16 years). He holds a Diploma in Dermatology (Cardiff) and is a Member of the Royal College of Surgeons (MRCS). More on Dr Gerard Ee.
A great deal of worry, and a great deal of wasted money, follows from one confusion, which is mistaking acne marks for acne scars. The two can look alike, but they sit at different depths and answer to different treatments. Establishing which is present is often the most valuable part of a consultation, since it prevents paying for resurfacing that is not needed and prevents waiting in vain for a real scar to fade. Of the patients who consult me asking about scar removal, a substantial share turn out to have marks, and saying so is the most useful thing that happens in the appointment.
Acne marks, PIH and PIE
Acne marks are flat changes in colour, with the skin’s texture left intact. Brown or tan marks are post-inflammatory hyperpigmentation (PIH), which is more common in deeper skin tones and represents excess pigment left after a breakout settles. Pink or red marks are post-inflammatory erythema (PIE), which arises from dilated blood vessels rather than from pigment and is more common in lighter skin. Both are temporary, because only the colour is altered, so they usually fade over weeks to months without resurfacing of any kind.
True scars, a change in texture
A true acne scar is a change in the skin’s texture, whether a depression, a raised area or an uneven surface produced by altered collagen. Scars, unlike marks, do not fade on their own, because the alteration sits in the collagen rather than in the pigment, and they need treatment that remodels collagen at depth. The types of acne scars guide covers these in detail.
A simple home test
There is a simple home check. Gentle stretching of the skin, or a light directed across it from one side, separates the two in most cases. If the discolouration flattens and the surface stays smooth, it is a mark. If a dip or bump that casts a shadow remains, it is a scar. The test prevents two costly mistakes, which are over-treating marks that would have faded anyway and under-treating scars that genuinely need help. In my experience the angled light is the step most often omitted at home, and flat overhead lighting conceals a shallow depression almost completely. Where the two coexist, which is common, the structural scar is treated while the pigment settles alongside.
Why the difference changes the treatment
Marks and scars sit at different depths and call for different tools. Pigment and redness are relatively superficial and respond to a gentle, lower-energy approach, good skincare, and devices designed for pigment rather than deep remodelling, such as Pico MLA. Scars are deep and need higher-energy, collagen-building treatment. Using an aggressive resurfacing laser to treat what is really PIH can irritate the skin and, in darker tones, even worsen the pigmentation, so the correct diagnosis dictates the correct intensity. Pico laser is the treatment patients most often request by name, and it may not always be the most clinically appropriate option, since a device built to disperse pigment does little for a depression in the skin’s surface.
How long marks take to fade
Red marks (PIE) often settle over a few weeks to a few months. Brown marks (PIH) can take several months, and sometimes considerably longer in darker skin. Sun exposure deepens and prolongs both, so photoprotection matters for pigment once the acne is controlled. The nuance concerns active acne, since heavy sunblocks can congest the skin and trigger breakouts, and while the acne is active it is preferable to prioritise controlling it and to use only light, non-comedogenic protection. Timelines of this kind are averages rather than promises, and a minority of patients are still watching a brown mark long after most have stopped noticing theirs.
Marks, scars and darker skin
Skin tone is significant here. Deeper skin tones are more prone to PIH and more vulnerable to pigment problems if treated too aggressively, so mark and scar are separated with particular care. Getting that judgement wrong costs more than a wasted session, because a mark treated as a scar can return as fresh pigmentation. The acne scars on dark skin guide covers the safe options.
How marks are treated
Once marks rather than scars are confirmed, treatment is gentler and often partly a matter of time. Red marks (PIE) tend to settle as the inflammation resolves, so the first decision is frequently to do less rather than more. Brown marks (PIH) respond to measures that target pigment, including topical agents and chemical peels, and the skin-of-colour literature supports cautious, lower-energy approaches with pigment prophylaxis (skin-of-colour optimisation). There is also evidence that PDRN, used mainly to speed healing, improves facial hyperpigmentation (PDRN anti-melanogenesis). Few patients are satisfied to hear that time is doing most of the work, and setting that expectation early prevents an expensive escalation to a device the marks never required.
The key mistake to avoid is treating marks as though they were scars. Resurfacing aimed at flat PIH risks irritation and, in darker skin, more pigment. Marks answer to patience, consistency and steady protection from ultraviolet light. Scars answer only to intervention that rebuilds collagen at the depth where it was altered.
What the research shows
Distinguishing pigment from scar matters because the two answer to entirely different interventions. Post-inflammatory hyperpigmentation is a recognised and usually self-limiting consequence of inflammation and of over-aggressive resurfacing. The great majority of darker-skinned patients can develop transient PIH after ablative CO2 laser, which is why gentler settings and prevention matter (skin-of-colour optimisation, PIH prevention in Asians). Polydeoxyribonucleotide (PDRN), better known as an aid to healing, also has anti-melanogenic properties and can improve facial hyperpigmentation (PDRN anti-melanogenesis). Evidence of this kind describes a group rather than an individual, so it may support a treatment choice without predicting one patient’s outcome.
What device studies show for marks and pigment
Modern device studies increasingly address marks and texture together while minimising pigment risk. A split-face study of a fractional 1064 nm picosecond laser combined with intense pulsed light achieved a 28% reduction in ECCA acne-scar scores over three sessions in patients who also had post-inflammatory erythema, improving both the scar and the redness (picosecond plus IPL study). Picosecond lasers in general cause far less post-treatment pigment change than ablative resurfacing (picosecond versus CO2 trial). A 28% reduction over three sessions is a meaningful improvement rather than a clearance, and I quote it when patients ask whether one course will finish the problem.
Device choice matters for pigment as much as for texture. In a split-face comparison, non-insulated microneedle fractional radiofrequency produced milder and more transient pigment and redness than ablative CO2 laser, which significantly raised the melanin and erythema indices at one and two months (radiofrequency versus CO2 study). For pigment-prone skin that difference is why gentler devices are preferred over aggressive resurfacing.
What causes brown marks (PIH)
Post-inflammatory hyperpigmentation forms when inflammation stimulates melanocytes, the skin’s pigment cells, to overproduce melanin. Where that pigment sits in the upper epidermis, the mark appears brown and tends to fade relatively quickly. Where inflammation has driven pigment deeper into the dermis, it appears greyer or blue-brown and clears far more slowly, sometimes over a year or more. Deeper skin tones, which carry more active melanocytes, are considerably more prone to PIH and to its longer-lasting dermal form. Continued sun exposure and ongoing inflammation both deepen and prolong the discolouration. In my experience the depth at which the pigment sits is what patients most need established at the first consultation, because a plan judged against the wrong timeline is abandoned before it can work.
What causes red marks (PIE)
Post-inflammatory erythema is a different process from pigmentation. It results from dilated or fragile superficial blood vessels left after inflammation, giving a pink to red or purplish flat mark. It is most visible in fairer skin and characteristically blanches, fading briefly under light pressure, because the colour comes from blood in the vessels rather than from pigment. That blanching is the most reliable way I have of separating red marks from brown ones at the chairside. PIE generally settles as the vessels return to normal, though the process can take several months. Anything that repeatedly dilates the vessels, including harsh scrubbing, heat and irritating products, slows that recovery, which is why the patients working hardest on their skin are sometimes the slowest to clear.
Topical treatment of brown marks
Once the acne is controlled, brown marks respond to a patient, consistent routine. Daily broad-spectrum sunscreen is the single most important measure, since ultraviolet light drives further pigment. Topical retinoids accelerate cell turnover and disperse pigment, while vitamin C, azelaic acid, niacinamide, tranexamic acid and kojic acid each reduce melanin production through a different mechanism. Hydroquinone can be effective but belongs under medical supervision and for limited periods rather than indefinitely. Improvement is gradual and is usually measured over months rather than weeks. The commonest error I see in a routine brought to the consultation is not too little treatment but too much, since several strong actives at once inflame the barrier and slow the process they were meant to accelerate.
In-clinic options for persistent marks
Where marks are persistent, in-clinic treatment may be considered, but the choice has to match the type of mark. For brown pigmentation, gentle pigment-targeting devices and carefully selected chemical peels are used, at lower intensity in darker skin to avoid provoking more pigment. For red marks, vascular treatments that target haemoglobin, such as a pulsed dye laser or intense pulsed light, can speed resolution. The governing principle is restraint, with intensity matched to the depth of the problem. A device is not always the answer, and a substantial share of the marks I am asked to treat would have settled unaided within the time a course of treatment takes.
How skin type changes the picture
Fitzpatrick skin type strongly influences both the risk and the management of marks. Higher Fitzpatrick types, common in Singapore, are far more prone to PIH, which also tends to last longer, so treatment is deliberately gentle and pigment protection takes priority. Fairer skin is comparatively more prone to PIE. Where a patient sits on this spectrum guides not only the choice of treatment but the energy at which it is used, which is why an in-person assessment is safer than a self-diagnosis. I cannot reliably predict at a first consultation how quickly a patient will clear a brown mark, and skin type narrows that range without closing it.
The role of sun protection
Sun protection matters because ultraviolet light darkens and prolongs pigmentation and can aggravate redness. Once the acne is controlled, daily broad-spectrum sunscreen is the most effective single measure for fading and preventing marks, and tinted sunscreens containing iron oxides add protection against the visible light that worsens pigment in darker skin. Neglected photoprotection explains more slow-fading brown marks than any deficiency in the topical routine.
When a mark is actually an early scar
Occasionally what looks like a flat mark overlies a textural change that is still developing. Where discolouration is slow to settle, re-examining the area under angled light after some months is worthwhile, because the picture at three months is often not the picture at twelve. Where the colour fades but a dip or unevenness remains, the problem is a true scar and is treated as one, with collagen-remodelling treatment rather than pigment-directed care. A first assessment is a judgement made on the evidence available at the time, and I revise it more often from mark to scar than in the other direction.
Common mistakes in treating marks
Several avoidable mistakes prolong marks or make them worse. The most damaging is treating a flat mark as a deep scar with aggressive resurfacing, which risks irritation and, in darker skin, a fresh wave of pigmentation. Neglecting daily sun protection once the acne is controlled undoes slow progress, since ultraviolet light continuously drives new pigment. Picking at residual marks reactivates inflammation and can convert a temporary mark into a lasting one. Overloading the skin with strong actives, in the hope of faster fading, inflames the barrier and slows recovery. And failing to distinguish brown pigment from red vascular marks leads to the wrong treatment, since the two respond to entirely different approaches. Outcomes still vary once all of these are avoided, and a minority of patients clear more slowly than a careful routine predicts, which is a reason to re-examine the diagnosis rather than to intensify the treatment.
The bottom line
Acne marks (PIH and PIE) are flat, temporary colour changes that usually fade with time. True acne scars are permanent textural changes that need collagen-remodelling treatment before they improve at all. The stretch-and-light test tells them apart in most cases, though an in-person assessment is safest, particularly in darker skin. Sixteen years of treating acne scarring has persuaded me that the diagnosis, rather than the device, decides whether a patient is satisfied a year later. Continue with do acne scars fade on their own or the complete treatment guide.
Frequently Asked Questions
What is the best product for acne scars?
No topical product removes a true scar, because a scar is a structural change in collagen rather than in colour. Products act on marks, with daily sunscreen after the acne is controlled, plus retinoids, vitamin C and azelaic acid, all of which fade discolouration over months. True scars need clinical treatment that remodels collagen at depth.
Can I remove acne scars naturally?
Skincare can fade post-acne marks over time but cannot remodel a true scar, because it does not act at the depth where the collagen was altered. Improving a real depression or raised scar requires treatments that rebuild collagen at that level.
What is the difference between PIH and PIE?
PIH is brown or tan pigmentation, more common in deeper skin tones, and represents excess melanin left after inflammation. PIE is pink or red marking from dilated superficial vessels, more common in lighter skin, and blanches under light pressure. Both are flat and usually temporary, unlike true scars, which are textural and do not resolve without treatment.
Will my acne marks fade on their own?
The majority of acne marks do fade without any treatment at all. PIH and PIE typically settle over weeks to months, although brown marks in darker skin may take considerably longer. True scars do not fade on their own and need treatment.
Key references
- Fractional CO2 laser: optimizing outcomes for pigmented atrophic acne scars in skin of colour. PubMed.
- Topical corticosteroids minimise post-inflammatory hyperpigmentation after ablative fractional CO2 in Asians. PubMed.
- Anti-melanogenesis properties of polydeoxyribonucleotide (PDRN). PubMed.
Comparative trials cited
- Feng H, Wu Y, Jiang M, et al. Fractional 1064 nm Nd:YAG picosecond laser combined with intense pulsed light for atrophic acne scars: split-face study. Lasers Surg Med. 2021;53:1356-1363. Journal.
- Yuan Y, He Y, Fang J, et al. Fractionated 1064 nm picosecond laser with holographic optics versus fractional CO2 laser for atrophic acne scars: randomised split-face study. Int J Dermatol. 2025;64:85-91. PubMed.
- Qu L, Sha S, He C, et al. Non-insulated microneedle fractional radiofrequency versus ablative fractional CO2 laser for facial atrophic acne scars: pilot randomised split-face study. Acta Derm Venereol. 2025. PubMed.
Written, medically reviewed and expert opinion by Dr Gerard Ee, aesthetic doctor and Founder & Medical Director of The Clifford Clinic. This article reflects my clinical experience treating acne scars in Singapore and is intended for general education, not medical advice. Treatment suitability, results, downtime and cost vary from person to person. Please arrange a consultation for advice specific to your skin.
