What causes acne scars, and why do they not fade?
Acne scars form when inflammation runs deep enough, and for long enough, to damage the dermis, the layer under the surface. The skin repairs that damage unevenly, with scar tissue. Where collagen is lost, the surface sinks. Where healing overshoots, a raised scar can form.
Nodules and cysts carry the greatest risk, along with picked spots and inflammation left untreated for a long time. Shallow blackheads and whiteheads often leave no scar. That is why early control of inflamed acne matters. See acne treatment in Singapore.
A depressed scar does not usually fill in with time, because lost collagen is not rebuilt unprompted and a tethered scar stays held down by its band. Old scars can still be treated. A scar of many years is mature and stable, which makes it predictable to plan around.
What are the main types of acne scars?
Most acne scars are pits in the skin, not surface marks. A rolling scar is pulled down from below, an ice-pick scar is a narrow, deep tract, and a boxcar scar has a flat floor with defined walls. Many people have a mix of these.
Treatment aims for smoother texture, shallower scars and a more even surface. Scars are not fully erased. Any change builds across a course, because collagen remodels over weeks.
Is it an acne scar, a red mark or a brown mark?
Not everything acne leaves is a scar. Red marks come from small blood vessels, not pigment, so pigment lasers and brightening serums miss the target.
| What you see | What it is | Path it usually takes |
|---|---|---|
| Flat red mark that fades under pressed glass | Post-inflammatory erythema: dilated small vessels | Acne control, then vascular settings or FSX Laser |
| Flat brown mark that stays under pressed glass | Post-inflammatory hyperpigmentation: pigment | Sun protection, topical care, pigment-directed laser. Resurfacing can deepen it |
| A pit or dip you can feel | Depressed scar: lost collagen, sometimes tethered | Scar treatment once acne is quiet |
| Firm, raised, itchy or growing scar | Hypertrophic or keloid scar: excess scar tissue | Injection into the scar, not resurfacing |
Which treatment suits which acne scar?
Tethered by fibrous bands from below, so release with subcision usually comes before resurfacing.
Wider scars with defined walls. RF microneedling and fractional resurfacing are often used.
Narrow, deep tracts where depth is the main problem. TCA CROSS applies a chemical focally into the scar.
Flat brown marks are pigment, and flat red marks are small blood vessels, so neither is a true scar. Each is treated on its own, separately from pitted scars.
Keloid and hypertrophic scars are managed differently. Treating them like pitted scars can worsen them.
Methods are often layered. For example, subcision can be followed by resurfacing.
How does Dr Sin Yong plan acne scar treatment?
Dr Sin Yong grades every scar himself at the first visit, before any plan is written. He covers six items: where each scar type sits, tethering, the Goodman and Baron grade, skin type and pigment history, acne activity and medicines, and how you have healed before. He reads scars under side light with the skin stretched, then assigns a tool to each.
Depth chooses between his two laser protocols: FSX Laser for superficial scars, and S3 Resurfacing for deep ice-pick and boxcar scars. With S3 he starts inside each pit with point shots, then runs fractional passes over the skin around it. On Fitzpatrick III to V skin, meaning medium to brown skin, passes are set less densely and stages are spaced by healing.
He declines scar treatment while acne is still active, because new scars would keep forming behind the work. His threshold is stability on examination, not a fixed waiting period. Flat brown and red marks stay out of the resurfacing plan.
Each stage is checked against standardised photographs before the next is timed. These stay in your medical record and are never published.
“A rolling scar is tethered from below. Resurfacing the surface of a tethered scar treats the wrong structure.”
In what order are acne scar treatments combined?
Most faces carry more than one scar type, so plans usually combine methods in a set order. Scars that have plateaued on one treatment are covered under 4D Scar Reconstruction.
Treatment Options
For mixed scarring, 4D Scar Reconstruction combines resurfacing, remodelling and collagen stimulation in layers.
How Common Options Compare
Fine needles create controlled micro-injuries. It may suit mild texture, and it is limited for deep or tethered scars.
Adds radiofrequency heat at a controlled depth. It is used for boxcar and rolling scars, and redness and pigmentation can follow.
Ablative columns are directed at texture and scar edges. Expect a recovery period with redness, and a higher pigmentation risk in darker skin.
Releases tethered scars from below. Bruising is common, and it does not treat surface texture on its own.
Which layer does each acne scar treatment reach?
A method can only act on the layer it reaches. This table compares methods by job and does not rank them. For more, see subcision vs laser.
| Method | Layer or target | Used for | Does not |
|---|---|---|---|
| Subcision | Fibrous bands below the dermis | Tethered and rolling scars | Treat surface texture |
| TCA CROSS | Floor of a narrow tract | Ice-pick scars | Treat wide, shallow scars |
| FSX Laser | Dermis, surface left intact | Superficial scars | Reach a deep scar floor |
| S3 Resurfacing | Fine columns into the dermis | Deep ice-pick and boxcar scars | Release a tether |
| RF microneedling | Dermis, through fine needles | Rolling and shallow boxcar scars | Release a tether |
| Radiesse (injectable) | Space under a released scar | Lost volume after subcision | Lift a scar still tethered |
S3 Resurfacing
S3 is Dr Sin Yong's fractional CO2 protocol on the DEKA SmartXide Tetra Pro, with depth and density set to a map of the scars and directed at texture and scar edges. It is one part of a plan, because resurfacing alone does not release a tethered scar. S3 stands for Stack, Scan and Sculpt, and the steps are set out on our CO2 laser page. Read our acne scar guide for more on how these options fit together.
How does non-ablative fractional laser differ from CO2?
The difference is whether the surface is removed. Fractional CO2 vaporises fine columns of skin. A non-ablative laser heats columns of dermis and leaves the surface in place. FSX Laser, the non-ablative protocol here, pairs 1540 nm erbium glass with 1927 nm thulium for superficial scars. S3 Resurfacing, the fractional CO2 protocol here, brings redness, swelling and fine crusting, and ablative energy carries a higher risk of darkening in medium to brown skin.
What can pico laser do for acne scars?
Pico laser is used for brown marks and fine, shallow texture, not depth. It does not divide a tethering band or reach the floor of an ice-pick tract, and darkening is its main risk in Fitzpatrick III to V skin. A 2023 randomised split-face pilot of 31 Asian patients measured scar score reductions of 39.11% with fractional picosecond laser and 43.73% with ablative Er:YAG laser, with pigmentation on 1 side against 8. It was small, and it used a 1064 nm picosecond laser with a micro-lens array, not the pico laser used here. [6] See pico laser for acne scars.
Can peels, facials or creams treat acne scars?
No. Facials and peels act at or near the surface, while a pit sits in the dermis below, so they have a supporting role at most. Over-the-counter creams cannot free a tether or fill a pit. A doctor may discuss a topical retinoid or other prescription agent after examining you, but no cream reaches a scar floor. High-strength acid bought online can cause burns and new scars.
When is surgery used for acne scars?
Rarely, for an isolated scar too deep or wide for non-surgical methods. Punch excision, elevation and grafting are done by a plastic surgery or dermatology specialist. Dr Sin Yong does not perform them. He refers you on.
Does acne scar treatment work?
No treatment fully removes an acne scar. Studies measure average change across a group, so they cannot predict your own result. Results vary.
A 2026 network meta-analysis of 56 randomised trials and 1,488 patients with moderate to severe atrophic scars found combination treatments generally outperformed single treatments, and called for larger, longer trials. It did not test the order of steps or the devices used here. [7] A 2021 review of 19 articles on the CROSS method reported 60% to 100% of acne scar patients showing over 25% improvement, noting small samples and a lack of control groups. [8]
Stretch Marks and Other Scars
Some of these methods can also be considered for stretch marks and other scars. Suitability depends on the type, age and location of the mark, so this is assessed in person.
Does acne scar treatment hurt, and what shows afterwards?
Most methods are done under local or topical anaesthetic, and tolerance varies.
| Method | Numbing and feel | What shows afterwards |
|---|---|---|
| Subcision | Local anaesthetic, then pressure and movement | Bruising, swelling, tenderness; surface intact |
| TCA CROSS | A brief sting on each scar | White frost, then a small crust |
| S3 Resurfacing | Local or topical anaesthetic, then heat | Redness, swelling, oozing, crusting, peeling |
| FSX Laser | Numbing cream | Redness, warmth, fine flaking |
| RF microneedling | Numbing cream, then warmth and pressure | Redness and pinpoint marks that flake |
How long is the downtime after acne scar treatment?
Resurfacing lasers and some microneedling bring a recovery period with redness. Subcision and injectables cause less surface disruption. Recovery varies by method and by person, and we give you a time estimate at assessment. No duration can be promised, and sun protection and control of active acne remain part of the plan.
Is acne scar treatment suitable for Asian and darker skin?
Asian and darker skin carries a higher risk of post-inflammatory pigmentation after laser. Device choice and settings are therefore calibrated conservatively, and sun protection between sessions matters. Please tell us about any past pigmentation after treatment.
Who is acne scar treatment suitable for?
It suits depressed scars you can feel, on skin where acne is now quiet, with the aim of a shallower, less visible scar.
| Group | What applies | What usually happens |
|---|---|---|
| Tends to suit | Ice-pick, boxcar or rolling scars, with acne controlled | Each scar graded, then a written plan |
| Waits first | Active acne, recent isotretinoin, infection or cold sore, a fresh tan, pregnancy or breastfeeding | Timing agreed at consultation |
| Weighed first | Keloid tendency, blood thinners, allergy to an anaesthetic or injectable | Methods adjusted or avoided |
| Referred on | An isolated scar too deep or wide, or an uncertain diagnosis | Plastic surgery or dermatology specialist |
Who Should Wait
Active or inflamed acne is usually controlled first, so that new scars do not form during treatment. See our article on acne flares. Teenagers are assessed case by case, with a parent or guardian present.
What to Expect
How do I prepare for treatment, and what is the aftercare?
Before treatment, tell the clinic about all medicines, including isotretinoin and blood thinners, and never stop a prescribed medicine on your own. Stay out of the sun, and pause strong retinoids and acids as advised. Afterwards, cleanse gently, leave crusts to shed, avoid direct sun and restart actives only when told. CO2 laser aftercare covers the resurfacing stage.
What are the risks, and when should I call?
Risks depend on the method and your skin. See complication care for more.
Redness and scabbing after resurfacing, a crust after TCA CROSS, bruising after subcision.
Prolonged redness, infection, a cold sore flare, a lump after an injectable, or a new scar.
The risk that matters most in Asian skin. Sun and picking raise the chance of it.
Increasing pain or swelling, a cluster of small blisters, or a wound that is not healing: call the clinic the same day.
Fever, spreading redness, pus, or a red hot lump: a doctor the same day, or A&E if none can see you.
Skin turning white, grey or mottled, or pain that is getting worse: urgent assessment by the injector or A&E now.
Change in vision or eye pain after filler or near the eye. Trouble breathing or swallowing, or swelling of the tongue or throat.
When should I see a doctor about acne scars?
See a doctor if acne is still leaving new marks or pits, if a scar is raised, itchy or growing, or if you cannot tell a mark from a scar.
How much does acne scar treatment cost in Singapore?
The cost depends on your scar types, their severity, the number of sessions and the methods used. We do not publish prices. You receive a quote after your in-person assessment.
Why is the fee given only after assessment?
A scar plan cannot be costed until the scars are examined, because tethering, depth and pigment risk only show in person. The fee then depends on your scar types and severity, the steps before resurfacing, the device chosen, the area treated and how many stages review shows. You receive a written quote after assessment. See acne scar treatment cost factors.
When can pimple scar treatment start?
Pimple scar treatment usually starts once active acne is under control, so that new scars do not form during the course. Acne scar removal in Singapore does not mean erasing a scar. The aim is a shallower, less noticeable scar. Young scars and marks are assessed differently from settled ones, so timing is set at your assessment.