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Acne scarring

Also known as: post-acne scarring, atrophic acne scars

Acne scarring is a lasting change in skin structure following acne inflammation and healing. Scars may be depressed, raised or mixed. Assessment distinguishes these structural changes from flat post-inflammatory colour changes and guides prevention, treatment selection and referral.

In plain English — Acne can leave lasting dents or raised areas after a spot has healed. Different scar shapes need different treatment approaches, and treatment can improve their appearance. Controlling ongoing acne helps prevent further scars.

Evidence status

Moderate

Established condition; treatment evidence varies. Scar assessment and prevention are established parts of acne care. Trials support improvement with selected interventions, but effect sizes, adverse effects and follow-up differ substantially. NICE recommends specialist-led management for severe scarring persisting a year after acne has cleared.

What acne scarring is, and the types encountered#

Acne scarring changes the contour or structure of skin after an inflammatory lesion heals. Atrophic scars form depressions; hypertrophic scars and keloids are raised. The focus here is assessment of acne-related scarring, especially depressed scars. See keloid and hypertrophic scarring for the raised-scar pathway.[3]

The familiar depressed-scar classification comprises icepick scars, which are narrow and deep; rolling scars, which create wider, shallow undulations; and boxcar scars, which are round or oval depressions. Mixed patterns are common. These are useful descriptive categories, not separate diagnoses that can be assigned a treatment from a photograph alone.[3, 9]

Flat colour changes require a separate assessment: post-inflammatory hyperpigmentation can remain after acne without an underlying depression or raised scar. Colour and contour can also be present together. Persistent papular scars can resemble residual spots, making diagnosis important before further acne treatment or extraction.[3]

Use of acne scarring in aesthetic practice#

The practical role is to recognise the concern, document its pattern, support skin care and help the person reach an appropriate treatment discussion. Ask whether the priority is texture, colour, discomfort or the effect on daily life. Record active acne, previous treatments, medicines, earlier healing problems and what improvement would feel worthwhile. Treatment is optional: a person who is comfortable with their scars does not need a procedure.[1, 4]

Ongoing acne vulgaris deserves attention alongside existing scars. NICE identifies greater severity and duration as scarring risks and advises against persistent picking or scratching. Gentle, suitable skin care and sun protection can support the treatment plan; camouflage is another legitimate option when wanted.[1][1, 4, 8]i

Contraindications and cautions#

Suitability belongs to the proposed intervention and the person’s history. Infection, active inflammatory disease, abnormal scarring, impaired healing and relevant medicines need clinical assessment before elective scar procedures. Record isotretinoin and other current or recent treatments accurately and obtain procedure-specific advice from the treating clinician. A study’s exclusion list should not be converted into a universal waiting-time rule.[4, 6]i

Prior pigmentation problems, skin tone, recovery requirements and the ability to follow aftercare affect the benefit–risk discussion. Raised scars should be assessed through their own pathway before any plan intended to remodel a depressed scar.[3, 9][1, 4]

Clinical uses and the evidence behind them#

Treatment families include laser resurfacing, chemical peels, microneedling, selected fillers and focal scar surgery. A clinician may address individual depressions surgically and then treat a wider area. The aim and evidence differ between these approaches, so a combination plan should explain the contribution expected from each component.[4, 9]

Ordinary microneedling

Alam and colleagues studied facial scars in a randomised split-face trial: 20 adults aged 20–65 enrolled and 15 completed three treatments. At six months from the first treatment, blinded scar scores on the treated side had improved from baseline by 3.4 points (95% CI 0.2–6.5); the control-side change was nonsignificant. This supports a possible appearance benefit in the studied setting, while the small sample limits precision. The reported 3.4 points is a within-side change, not an estimated advantage over control. Northwestern departmental funds supported the trial; the lead author disclosed other commercial relationships.[6]

Energy-based treatment

A 2023 randomised study compared one fractional CO2 treatment with one RF-microneedling treatment in paired facial areas of 15 people with moderate-to-severe scars. Both produced a median one-point texture improvement on a 0–10 scale at three months. This is evidence of modest short-term improvement under those study conditions; it does not set a universal treatment ranking. Funding could not be established from the retrieved abstract.[7]

Interpreting the wider evidence

The 2016 Cochrane review included 24 trials and 789 adults, mainly with facial atrophic scars. Its evidence ranged from very low to moderate certainty; small studies, varied assessments and limited follow-up complicated comparisons. Its search ended in November 2015, so it is a historical synthesis rather than a complete account of current devices. NICE subsequently considered both evidence and clinical context in its specialist-management recommendations.[5][1, 2]i

Selecting an assessment and treatment approach#

Selection begins with a map of the problem: depressed or raised scars, individual lesions or a wider textural change, accompanying colour changes, and any active acne. Different mechanisms serve different goals: focal surgery can lift or remove selected scars, fillers can restore volume to suitable depressions, and resurfacing or needling addresses an area through a healing response. These are clinical treatment categories, not instructions for delivering them.[4, 9]

Discuss likely improvement, staged care, expense, recovery and the possibility that more than one approach may be considered. Consistent photographs and a recorded baseline can help assess change; the person’s own priorities should remain alongside any clinician-rated score.[1, 4][6]

Adverse effects and their management#

Pain, redness, disruption of the skin surface and pigment changes vary with the procedure. In Hendel’s paired-area trial, CO2 caused more intense early redness and loss of skin integrity, whereas RF needling was more painful. One measure of tolerability therefore cannot stand in for all recovery outcomes.[7][5]i

Follow the treating clinician’s aftercare and escalation instructions, including appropriate sun protection and review of troublesome reactions. A scar or treated area that becomes warm, increasingly swollen or painful, or discharges pus needs urgent medical assessment rather than further exfoliation or needling.[1, 8]

Referral and scope boundaries#

NICE advises considering dermatology referral when acne is causing scarring; prevention does not need to wait until all acne has resolved. For severe scarring persisting a year after acne has cleared, NG198 recommends referral to a consultant dermatologist-led team with scar expertise. In that setting, it lists CO2 laser alone or after punch elevation, or a glycolic acid peel, for consideration. Local service access and the individual’s clinical circumstances need checking.[1][1, 2]i

Uncertain diagnosis, raised or symptomatic scars and significant distress merit clinical assessment. NICE also addresses mental-health referral where acne-related distress or a disorder is significant. Referral should respond to the impact on the person, not just the number of scars. Competence or permission to perform any procedure is not established here.[1, 8]

Mechanism of action#

Inflammation and repair alter the dermal tissue that supports the skin surface. In a simplified model, inadequate replacement of lost support produces a depression, while excessive scar tissue produces a raised lesion. Clinical appearance therefore reflects the healing response as well as the original acne lesion.[3, 4]i

Scar treatment can pursue tissue remodelling, volume restoration or mechanical correction of a depression. These are complementary rationales rather than one universal instruction to “make more collagen”. The wound-healing cascade explains the broader biology; the relevant procedure entry describes its mechanism.[3, 4]i

Commonly misstated claims#

The one-year threshold

Claim heard:“Every acne scar finishes healing at exactly one year.”

Literature finding:NICE’s rationale combines the committee’s experience of remodelling with the strength of the evidence and service-resource considerations when explaining its severe-scarring referral threshold. It does not establish a universal biological deadline.[1, 2]i

Supported statement: The one-year criterion belongs to a specified clinical pathway; individual scar maturation and assessment remain variable.

Percentage improvement

Claim heard:“The needling trial showed that 41% of scars disappeared.”

Literature finding:That figure was the mean improvement perceived by participants in Alam’s small trial. It was not a count of removed scars or the blinded assessors’ rating.[6]

Supported statement: Patient-reported improvement and measured scar change are different outcomes and should be identified as such.

Similar results and equivalence

Claim heard:“No statistically significant difference proves that treatments are equally effective.”

Literature finding:One Cochrane comparison of laser with combined peeling/needling at week 48 had a risk ratio of 1.00, but a 95% CI of 0.60–1.67, only 26 participants and very-low-certainty evidence.[5]i

Supported statement: An imprecise comparison can leave clinically important differences unresolved; equivalence requires suitable evidence.

Areas of remaining uncertainty#

  • Durability: many studies assess months rather than years. Discuss maintenance and future change without guaranteeing a permanent endpoint.[5][7]
  • Transfer between patients: facial-study results do not automatically quantify outcomes on the trunk, in different scar mixtures or after different treatment histories. Match the evidence to the case.[5][6]
  • Meaningful improvement:a score change, satisfaction rating and visible change may answer different questions. Agree the person’s priorities before choosing an outcome measure.[1, 4][6]

Frequently asked questions#

Does every acne scar need treatment?

No. Decisions depend on the person’s priorities, symptoms and the impact on life. Observation, supportive care or camouflage may be appropriate choices.[1, 4, 8]i

Who should assess a mixture of dents and raised scars?

A clinician experienced in scar diagnosis and management. Different patterns can coexist and require different treatment aims.[3, 9]

Can treatment be discussed while acne is still active?

Yes. A discussion can address current acne, prevention and later scar options together, while the treating clinician decides when any particular procedure is appropriate.[1][1, 4]

References#

Each source is graded by evidence tier. Tier 4 material (manufacturer documents, expert consensus, practitioner experience) is useful for protocol and context, and is never presented as equivalent to independent clinical evidence.

  1. NICE. Acne vulgaris: management. NG198. Recommendations 1.2.4, 1.4.2–1.4.5, 1.5.6 and 1.8. Published 2021; current recommendations accessed 16 September 2026.Tier 1Supports: Prevention, ongoing-acne treatment, psychological impact, referral and specialist management of severe persistent acne scarring.Funding / interest: NICE clinical guideline; public guideline-development body, not product-sponsored evidence.
  2. NICE. Acne vulgaris: management. NG198. Rationale and impact: managing acne-related scarring. Accessed 16 September 2026.Tier 1Supports: Committee reasoning: different scar patterns, remodelling, evidence limitations, specialist expertise and resource considerations behind recommendation 1.8.2.Funding / interest: Same publicly developed NICE guideline as source 1; this rationale is not an independent clinical study.
  3. American Academy of Dermatology. Acne scars: signs and symptoms. Updated 8 December 2023. Accessed 16 September 2026.Tier 4Supports: Depressed, raised and papular acne-scar appearances, collagen-related healing explanation and distinction from flat post-inflammatory spots.Funding / interest: Page acknowledges Ortho Dermatologics support and states that all content was solely developed by the American Academy of Dermatology. Patient information, not a systematic review.
  4. American Academy of Dermatology. Acne scars: consultation and treatment. Updated 8 December 2023. Accessed 16 September 2026.Tier 4Supports: Individual assessment, current acne and medicines, treatment families, scar surgery, filler volume restoration and separate raised-scar management.Funding / interest: Page acknowledges Ortho Dermatologics support and states that all content was solely developed by the American Academy of Dermatology. Same disclosure as source 3.
  5. Abdel Hay R, Shalaby K, Zaher H, Hafez V, Chi CC, Dimitri S, Nabhan AF, Layton AM. Interventions for acne scars. Cochrane Database of Systematic Reviews. 2016;(4):CD011946. doi:10.1002/14651858.CD011946.pub2. PMID:27038134.Tier 1Supports: Historical synthesis of 24 RCTs and 789 adults, mainly facial atrophic scars; very-low to moderate certainty, imprecise comparisons and limited follow-up. Searches ended November 2015.Funding / interest: Review-specific support and author-conflict details were not available on the personally retrieved Cochrane summary/complete abstract; independence is not inferred.
  6. Alam M, Han S, Pongprutthipan M, et al. Efficacy of a needling device for the treatment of acne scars: a randomized clinical trial. JAMA Dermatology. 2014;150(8):844–849. doi:10.1001/jamadermatol.2013.8687. PMID:24919799.Tier 2Supports: Assessor-blinded split-face needling trial: 20 adults enrolled, 15 treated/completed, ages 20–65, facial scars, three treatments and assessment at three and six months from first treatment. Within-side score changes and patient-perceived improvement.Funding / interest: Northwestern University dermatology departmental research funds; funding source participated throughout study and publication. Alam disclosed unrelated Amway/Leo Pharma consulting, institutional studies supported by Allergan, Medicis, Bioform and Ulthera, and Elsevier royalties.
  7. Hendel K, Karmisholt K, Hedelund L, Haedersdal M. Fractional CO2-laser versus microneedle radiofrequency for acne scars: a randomized, single treatment, split-face trial. Lasers in Surgery and Medicine. 2023;55(4):335–343. doi:10.1002/lsm.23655. PMID:36934435.Tier 2Supports: Fifteen people with moderate-to-severe acne scars; randomised facial test areas, one treatment, three-month assessment. Texture improved with both; local reactions greater after CO2, pain greater with RF needling in this study.Funding / interest: Funding and conflict declarations were not available in the personally retrieved PubMed and publisher abstract views; academic affiliations alone do not establish independence.
  8. NHS. Scars. Reviewed 18 September 2023. Accessed 16 September 2026.Tier 4Supports: General scar support, camouflage, discomfort, psychological concerns and urgent assessment for warmth, swelling/pain or pus.Funding / interest: NHS patient information; no product sponsor stated. Not a formally evidence-graded clinical guideline.
  9. Jacob CI, Dover JS, Kaminer MS. Acne scarring: a classification system and review of treatment options. Journal of the American Academy of Dermatology. 2001;45(1):109–117. doi:10.1067/mjd.2001.113451. PMID:11423843.Tier 4Supports: Proposed icepick, rolling and boxcar classification and selection of reconstructive approaches according to scar type. Abstract retrieved, not treated as comparative trial evidence.Funding / interest: Funding and conflicts were not established from the personally retrieved official abstract.