How to remove acne scars?

Different types of acne scars.

There are several types of scars from acne, which it is important to distinguish for effective management. Note that a mark is considered a scar when it remains visible one year after the lesion has healed.

Atrophic scars : Atrophic scars appear as depressions in the skin. They develop when a spot does not heal and the connective tissue that forms is insufficient. Their size and depth vary. They present in three forms. The first are ice pick or V-shaped: narrow and deep. The second are U-shaped or crater-like: wide, shallow, with sharp or rounded edges. The third are quadrangular: wide and deep.
Hypertrophic scars : Hypertrophic scars, also called raised scars, are swollen protrusions of skin tissue. They form when a second skin layer covers scar tissue during the healing phase of an acne lesion. These scars arise from excess collagen.

Acne scars are often mistaken for red marks (post-inflammatory erythema) or brown marks (post-inflammatory hyperpigmentation) left by spots. These can remain visible for several months on the skin. They affect superficial layers of the epidermis without causing depressions or raised areas.

How to minimise acne scarring?

If acne is severe, there is no effective treatment to fade or remove scars, except through surgery and aesthetic medicine.

However, before considering any treatment for acne scarring, ensure the inflammatory phase has ended. If you have had treatment with isotretinoin (known as Roaccutane), it must have concluded at least six months ago. This is important because, besides being ineffective in some cases, treating acne scarring can trigger an inflammatory response and a new acne flare-up. To reduce scarring left by acne lesions, here are the available options.

Treatment No. 1 for acne scars: dermatological peeling.

A dermatological peel is a procedure performed to remove atrophic and hypertrophic scars. It involves applying a potent exfoliant to the skin, either phenol at 15 to 60 per cent or trichloroacetic acid (TCA) at 10 to 70 per cent. Chemical peeling causes controlled destruction of part or all of the epidermis, with or without the dermis, leading to the shedding of superficial lesions followed by regeneration of new epidermal and dermal tissue, resulting in smoother skin with less visible scarring. After a dermatological peel the skin is sensitive. A healing cream should be applied daily for weeks after treatment and sun exposure should be avoided.

A study evaluated the effects of a 70% TCA peel on atrophic scars in 53 patients. They were followed for three months. A good or excellent improvement (>50%) was observed in 66% of participants. In 81.1% of cases, participants reported satisfaction or high satisfaction.

Peeling dermatologique au TCA (70%) : avant/après à 3 mois. — Dermatological TCA peel (70%): before and after at three months.
Source: Mittal A. et al. Therapeutic response to 70% trichloroacetic acid CROSS in atrophic acne scars. Dermatologic Surgery (2015).

Treatment No. 2 for acne scars: microdermabrasion.

Microdermabrasion is a non-invasive, relatively gentle method that can reduce acne scars. Its principle is based on a controlled mechanical exfoliation of the superficial layers of the epidermis, using microcrystals of aluminium oxide projected at high speed, or via a diamond abrasive tip. This abrasion stimulates cell renewal, promotes removal of dead cells, and accelerates skin regeneration. By inducing mild local inflammation, microdermabrasion triggers collagen production and improves skin texture. To achieve perceptible results on acne scars, a protocol of multiple sessions is required — between five and ten — separated by intervals of two to three weeks. Microdermabrasion has high tolerability and a low risk of side effects when performed by a trained professional.

Treatment No. 3 for acne scars: laser therapy.

The laser is effective for treating hypertrophic scars. It targets specific skin areas with successive laser pulses to stimulate cell renewal. A broad range of lasers exists: Fraxel laser, CO2, etc... This procedure It aims to even the skin by correcting small depressions or elevations caused by acne. Multiple sessions are likely needed to reduce scars and achieve lasting results. Some studies also show that combining the laser with another treatment can be effective for removing acne scars.

It is possible, for example, to combine fractional ablative treatment with CO2 with fractional microplasma radiofrequency treatment. A study of 64 participants showed this combination reduced acne scar visibility more than the laser alone. Another study with 30 participants used CO2 fractional laser on one side of the face and CO2 fractional laser followed by intradermal injections of platelet-rich plasma (PRP) on the other side of the face. In both groups, results were satisfactory. However, combining treatments led to greater improvement of atrophic scars.

Treatment No. 4 for acne scarring: hyaluronic acid injections.

Injections of hyaluronic acid may reduce shallow atrophic scars, such as wave-shaped ones. The principle relies on targeted injection of hyaluronic acid beneath the skin depression to restore volume and smooth the skin surface. This mechanical filling reduces the visual irregularity of the epidermis. However, hyaluronic acid is a molecule resorbed by the body, so its effects are temporary: a new injection is required every six to twelve months to maintain results. Considered safe, hyaluronic acid injections remain an aesthetic medical procedure that must be practised by a professional and carries potential side effects (oedema, redness, infections).

Treatment No. 5 for acne scars: radiofrequency.

Radiofrequency relies on the emission of high-frequency electromagnetic waves capable of heating deep dermal layers without harming the epidermis. This thermal effect stimulates fibroblast activity, the cells responsible for collagen and elastin synthesis. By reactivating skin regeneration, radiofrequency improves dermal density and firmness. It is indicated to reduce moderate atrophic scars, partially restoring lost volume. The protocol involves three to four sessions, each spaced about one month apart to induce collagen production and achieve a visible lasting result. Several studies have investigated radiofrequency to diminish acne scars. The results of some are presented in the table below.

Authors	Number of patients	Radiofrequency type	Number of sessions	Results
Kim et al.	52	Fractional microneedle radiofrequency	Four sessions	73.1% of patients showed an improvement.
Chandrashekhar et al.	31	Microneedle radiofrequency	Four sessions over six months (every six weeks)	80.64% of grade 3–4 scars improved by two grades, 19.35% by one grade
ELAWAR & al.	…	Microneedle radiofrequency	two to four sessions (every four weeks)	Significant improvement in scarring
Kim et al.	Not specified	Fractional bipolar radiofrequency	Four sessions (every three weeks)	Significant improvement in elasticity and increased synthesis of procollagen types I and III
QIN et al.		Radiofrequency (unspecified type)	four sessions (at four-week intervals)	Significant improvement in acne scarring

Summary of studies investigating the efficacy of radiofrequency for acne scars.

Source: NOWICKA D. et al. Methods for improving acne scars used in dermatology and cosmetology: a review. Journal of Clinical Medicine (2022).

Treatment No. 6 for acne scarring: corticosteroid injections.

Another option for treating acne scars, notably hypertrophic scars, is intralesional corticosteroid injections. This involves injecting a cortisone derivative – most often triamcinolone acetonide at concentrations of 10 to 40 mg/mL – directly into the lesion. The aim is to reduce scar volume. This is achieved by the antimitotic effect of the injected corticosteroids, which inhibit the proliferation of fibroblasts and keratinocytes responsible for excessive collagen production. The corticosteroids may promote the breakdown of accumulated collagen by inhibiting a protective molecule of the deposits, alpha-2-macroglobulin.

To optimise product distribution within scar tissue, gentle cryotherapy with liquid nitrogen may be applied 10 to 15 minutes before injection. Use of a topical anaesthetic cream or lidocaine injection is often recommended to improve patient comfort. Potential adverse effects include depigmentation, skin atrophy, telangiectasia, or, less commonly, local infection.

Treatment No. 7 for acne scars: microneedling.

Microneedling is a skin-stimulation technique that consists of creating micro-perforations on the skin’s surface using multiple fine needles with a length under 0.5 mm. These superficial micro-injuries act as a repair signal, triggering a regenerative cascade in the skin. The response produces new collagen fibres and remodels the skin structure, helping reduce the visibility of acne scars. Its invasiveness is low. The treatment can be carried out in a clinic with limited downtime and few side effects under professional supervision.

A prospective clinical study assessed microneedling for atrophic acne scars. Ten patients with various atrophic scar types completed six sessions at two-week intervals over three months. A visible improvement in scars was noted in all participants. Histological analyses revealed a significant increase in type I, III and VII collagens, as well as newly synthesised collagen. A significant reduction in total elastin was observed, suggesting remodelling of the extracellular matrix towards a more functional structure. The table below provides further details on extracellular matrix changes following microneedling.

Criteria	Before treatment	One month after the start of treatment (two sessions)	Three months after the start of treatment (six sessions)
Epidermal thickness (µm)	63 ± 4.9	72 ± 7.1
Type I collagen (%)	tags and keeping 67,1 ± 4,2	` tags and preserve `70,4 ± 5,4	78.2 ± 6.8
Type III collagen (%)	61,4 ± 3,6	… 65,5 ± 6,1	74.3 ± 7.4
Type VI collagen (%)	` tags and keep `15,2 ± 2,1		21.3 ± 1.2
Newly synthesised collagen (%)	14,5 ± 5,8	15.8 ± 5.3
Elastin (%)	51.3 ± 6.7	50,1 ± 4,7	46,9 ± 4,3

Quantitative analysis of epidermal thickness and extracellular matrix proteins before and after microneedling treatment for post-acne atrophic scars.

Source: Medhat W. et al. Microneedling therapy for atrophic acne scars: an objective evaluation. Journal of Clinical and Aesthetic Dermatology (2015).

Advice : Since acne scars are difficult to eliminate, adopt measures to prevent their onset. Avoid touching lesions and do not delay consulting a dermatologist if you have acne. The more severe the acne and the later treatment begins, the higher the risk of scarring.