How does a scar change after laser treatment ?
After laser treatment, a scar may become less visible through improvements in its surface contours, colour or texture. The change achieved mainly depends on the scar characteristic targeted by the laser.
A depressed scar may become shallower and cast less shadow on the skin surface. A red scar may gradually lose its colour. A thick scar may flatten and soften. When the scar has an uneven surface, laser treatment can also improve skin texture.
Laser treatment therefore does not make the scar disappear. It can make it less noticeable by reducing differences in surface contours, colour or texture compared with the surrounding skin.
Can laser treatment make a scar disappear completely ?
No. No laser can make a scar disappear completely. Treatment can make it less visible, but does not restore skin identical to what existed before the injury.
A scar consists of repair tissue whose structure differs from normal skin. Laser treatment can remodel this tissue, stimulate collagen production and improve the scar's surface contours or texture without eliminating the scar tissue.
The American Academy of Dermatology also points out that laser treatment can make a scar less visible, but cannot erase it completely.
The aim of treatment is therefore to reduce the scar and its contrast with the surrounding skin rather than make it disappear.
Is laser treatment effective for depressed scars ?
Fractional laser treatment can reduce the depth of certain atrophic scars and make the skin surface more even.
An atrophic scar forms when skin repair does not restore enough tissue. The scar then remains lower than the surrounding skin.
A fractional laser creates multiple microscopic zones of ablation in the skin. This stimulation triggers a new repair phase. Fibroblasts produce collagen and the dermis gradually remodels.
The scar may therefore become shallower. The shadows it casts under certain lighting also diminish, helping make it less visible.
Results are particularly well documented for atrophic acne scars. A systematic review published in 2025 reports improvement of 30 to 70 % after fractional CO₂ laser treatment in most patients included in the studies analysed.
This range describes results observed in several studies ; it cannot predict the percentage improvement of a particular scar.
Do laser results vary according to the type of acne scar ?
No. Acne scars respond differently to laser treatment according to their shape and depth.
Boxcar scars form depressions with relatively sharply defined edges. When they are superficial or moderately deep, the remodelling induced by a fractional laser can reduce their depth.
Rolling scars are wider and give the skin an undulating appearance. Some are pulled downwards by fibres connecting the dermis to deep tissues. Laser treatment can improve the skin, but does not cut these adhesions. Subcision may then be necessary.
Ice pick scars are narrow but extend deep into the dermis. Fractional laser treatment alone is often less effective ; a continuous ablative laser session must be added.
Systematic reviews confirm that fractional laser results vary according to the type and severity of acne scars. Deep scars may require a combination of several techniques.
The result therefore depends on the precise types of scars present on the face.
Is laser treatment effective for surgical scars ?
Laser treatment can improve the surface contours, suppleness and colour of certain surgical scars.
A surgical scar naturally changes over several months. Initially, it may be red, firm and slightly raised. It then gradually softens and fades.
When the scar remains thick or uneven, certain fractional lasers can promote scar tissue remodelling. If persistent redness is the main problem, a vascular laser can be used to target the blood vessels specifically.
A meta-analysis published in 2025 investigated fractional CO₂ laser treatment for surgical scars. It included 14 controlled trials and 492 participants . The authors found a significant improvement in scars, particularly when treatment began within the first month after surgery.
It is therefore not always necessary to wait several months before treating a surgical scar. The appropriate timing depends on the wound's condition and how the scar is developing.
How long does it take to see laser treatment results on a scar ?
Laser treatment results on a scar appear gradually and may continue to evolve for several months after the session.
Immediately after treatment, the skin may be red, swollen, peeling or have small crusts. These reactions reflect the healing phase and do not allow the laser result to be assessed.
Dermal remodelling then continues for several weeks to several months. Fibroblasts produce new collagen, which gradually reorganises within the tissues.
Improvement in the scar's surface contours and texture is therefore gradual. The American Academy of Dermatology states that several months may be needed to fully appreciate the results of laser scar treatment.
The disappearance of redness and crusts therefore does not represent the final result : scar remodelling continues after the skin surface has healed.
Is a single laser session enough to reduce a scar ?
A single laser session can already improve a scar, but several sessions are generally needed for a more substantial result. The number of sessions and their spacing mainly depend on the type of laser and scar characteristics.
With a non-ablative fractional laser, 4 to 6 sessions are generally needed, spaced approximately 3 to 6 weeks apart. Because the action is gradual and recovery effects generally milder, several successive treatments are necessary.
With an ablative fractional laser, such as CO₂ or Erbium, treatment is more intense. In practice, 3 to 4 sessions may be performed, generally spaced at least 4 to 8 weeks apart to give the skin time to heal and skin remodelling time to continue.
The protocol also depends on scar depth and extent. An isolated superficial scar may sometimes improve sufficiently after one or a few sessions, whereas numerous deep acne scars generally require several treatments.
For surgical scars, a meta-analysis published in 2025 shows that a single early fractional CO₂ laser session can already bring improvement. However, most studies analysed involved 2 to 3 sessions or more.
There is therefore no single number of sessions suitable for all scars. As a guide, the protocol generally comprises 4 to 6 sessions for a non-ablative fractional laser and 3 to 4 sessions for an ablative fractional laser, with spacing adapted to treatment intensity and healing.
Why does laser treatment not work on certain scars ?
Laser treatment may be ineffective for some scars when their depth or the presence of fibrous adhesions cannot be corrected by dermal remodelling alone.
Ice pick scars are narrow but extend deep into the skin. Laser treatment may improve the overall texture of the treated area without reaching the base of these scars sufficiently to correct their depth.
Rolling scars may present another problem : some are pulled downwards by fibrous adhesions connecting the skin to deep tissues. Laser treatment does not cut these fibres and therefore cannot release the scar on its own.
In these situations, another technique may be necessary. A continuous ablative laser or medium-deep peel can be used for certain deep scars, while subcision releases the adhesions responsible for some rolling scars. Several treatments may also be combined when different types of scars are present.
Repeating sessions with the same laser is therefore not always useful when a scar shows little improvement. The cause of its depth or tethering must be identified to select treatment suited to its structure.
What do studies say about laser scar treatment results ?
Scientific studies confirm that lasers can improve scars, but the extent of the result varies according to the type of scar, the laser used and the protocol performed.
For atrophic acne scars, fractional CO₂ and Erbium lasers have demonstrated clinical effectiveness. A systematic review published in 2025 reports improvement of 30 to 70 % with fractional CO₂/ Erbium laser treatment in most studies analysed.
For surgical scars, studies also show a benefit from fractional CO₂/ Erbium, particularly when treatment begins early.
The literature therefore confirms the effectiveness of laser treatment for certain scars without allowing precise prediction of results in a particular patient. The result depends on the type of scar, the laser chosen and the protocol used.
Article written by Dr Valeria Romano
Dr Valeria Romano supports each patient with a comprehensive approach to the aesthetics of the face, body and intimate areas, and to skin and hair quality. Every treatment is based on a personalised medical assessment.
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