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Non-ablative fractional laser: it is the side that lost to the picosecond laser — the same trial

On acne scars it was matched against a 1064 nm picosecond laser across the two sides of the face and lost, 42% against 55% ECCA reduction. Pain and side effects were also higher on this side. And a separate trial reported normal wound healing when treating within one month of finishing isotretinoin — with 10 people.

Last checked Sep 28, 2026

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What it is: A laser that puts heat into columns below without removing the surface. The 1550 nm erbium-glass laser is the typical one.
What it is used for: For acne scars, wrinkles and texture.
How it is said to work: It leaves the outer layer in place and creates columns of heat beneath, and collagen is said to rebuild as those heal. Unlike the CO2 and erbium lasers, it does not vaporise the surface.

There are no numbers and no citations in this box. What has been established, and how far, is below.

At a glance

Session length: 20–40 min
Pain: PainfulReported in a trialIn the trial above it hurt more than the picosecond laser — 5.6 against 4.3. Note the comparison is against another laser.
Downtime: 2–5 days
Sessions: 3–4 sessionsReported in a trialThe two trials above used four sessions at three-week intervals and three at four-week intervals.
How long it lasts: 2 monthsReported in a trialThe 2020 trial read to eight weeks after the final session. We have not verified material beyond that.
Relative cost: Higher
How well established: Early research

“Reported in a trial” means a number a study on this page actually reported. “Typical range” is not a measured value but roughly how it is usually done, and it varies by clinic and by person.

Cost is not an amount but a band: where this procedure falls when the ones on this site are lined up per session, or per area treated. Real prices differ several-fold by clinic and by how much is treated, so they are not given here. Surgery is measured on a different scale and cannot be compared with this band.

This is not how large the effect is but how well confirmed it is. It shows the highest grade among the findings on this page.

Korean classification Being checkedThe regulatory class has not yet been confirmed against a primary document. It will be filled in once it is.

A non-ablative fractional laser puts columns of heat beneath the skin without removing the surface. The 1550 nm erbium-glass laser is the typical one.

Set it beside the other fractional laser pages on this site.

fractional CO2 and Er:YAG — vaporise the surface (ablative)
this page — leave the surface and work beneath (non-ablative)

Leaving the surface means faster recovery and less gained per session is the usual account.

Something has to come first on this page.

The first entry below is the same trial as the second entry on the picosecond laser page. There it is written up as the side that won; here as the side that lost.

It is the same material. When this site puts one trial on two pages it says so, and internally marks it as one trial so that the evidence is not counted twice. Read the two pages side by side, but do not think there are two pieces of material.

The second entry is of a different kind. Not about effect, but about when you are allowed to start — and it has 10 people.

This site does not deal in prices, clinics or reviews.

What is established

Not established

On acne scars it lost to the picosecond laser

A 2020 Korean trial in JEADV. Prospective, randomised, split-face controlled, over 17 weeks.

The faces of 25 patients were split at random:

one side — a 1064 nm Nd:YAG picosecond laser (diffractive optical element), four sessions at three-week intervals
the other — a 1550 nm non-ablative fractional laser (NAFL)

Follow-up ran eight weeks after the final sessions.

Results:

ECCA per cent reduction — NAFL 42% against picosecond 55% (P < .05)
pain — 5.6 against 4.3 (more on this side)
treatment-related side effects — higher on this side (P < .05)
histology showed, on both sides, elongation and increased density of neocollagen, elastic fibres and mucin through the dermis

How to read it.

First, losing does not mean 'it does nothing'. ECCA fell 42%. And histology showed changes in collagen and elastic fibres. Something happened. The thing next to it simply did more.

Second, we still cannot write 'it works'. This trial has no untreated side. Both sides had a laser, and that 42% has 17 weeks of time and the natural course of acne scarring mixed into it. Which is why the badge on this entry reads 'not established'.

Third, 25 people, in Asian patients. The authors attached that condition to their conclusion.

Fourth, that the histology ran the same way on both sides is worth reading. It allows the reading that the two devices do a similar kind of thing, to a different degree. If so, the choice becomes one about recovery time and pain — and on this trial the picosecond side was better there too.

Fifth, this trial also appears on the picosecond laser page. Same 25 people, same 17 weeks.

Randomised controlled trial in people · 25 participants · 17 weeks · Compared with another active ingredient · Funding not declared · Endpoint scores from blinded assessors PMID 32603006

Early research

Wound healing was normal within a month of finishing isotretinoin — with 10 people

A 2017 trial at the University of Utah. Different in kind from the other entries. It asked not about effect but about when you may start.

The background first. Because of reports of poor wound healing and scarring after oral isotretinoin, the advice in circulation has been to wait six months after finishing before safely starting laser treatment.

This site does not cover swallowed prescription drugs. We include this entry because those six months are a long time in practice for someone wanting to deal with acne scarring.

The design:

10 patients with acne scars who had just completed isotretinoin
one side of the face treated with a 1550 nm erbium-doped non-ablative fractional laser, three sessions four weeks apart, started within one month of finishing isotretinoin
the untreated side acted as the control
two blinded dermatologists evaluated wound healing, adverse effects and scar improvement

Results:

all patients demonstrated normal wound healing
neither hypertrophic scars nor keloids were observed
acne scar improvement was satisfactory

The authors conclude: NAFL within one month of completing isotretinoin appears to be well tolerated, and dermatologists should reevaluate the current recommendation to wait six months. And immediately after — other larger studies are necessary to further challenge this dogma.

How to read it.

First, 10 people. And it is a trial about safety. Safety is the problem of finding rare things, and rare things cannot be found in 10 people. 'It did not happen to 10 people' is not 'it does not happen'.

Second, the strength of this trial is its design. There is an untreated other side and the assessors were masked. Those are uncommon conditions in this layer, which is why this entry sits a grade above the one before it.

Third, 'improvement was satisfactory' comes with no number. The abstract did not quantify it. So do not read this entry as evidence of effect.

Fourth, the authors themselves wrote that larger studies are necessary. They put out a result that unsettles received practice and wrote its limit in the same breath, and this site carries both sentences.

So it sits at 'early evidence'. The direction is clear and the size is small.

And this is not guidance. When laser treatment can begin after isotretinoin is decided in a consultation. What this page does goes as far as setting out what material that conversation has to work with.

Randomised controlled trial in people · 10 participants · 12 weeks · Compared with no treatment · Funding not declared · Endpoint scores from blinded assessors PMID 28853175

Known risks

It does not remove the surface, but it does put heat in. Redness, swelling and a sandpaper roughness last some days.
In the trial above, pain and treatment-related side effects were higher than with the picosecond laser.
Post-inflammatory hyperpigmentation is a known risk of fractional lasers generally, and more of a problem on more pigmented skin. Note that the 2020 trial above was in Asian patients.
Sun protection is central to care before and after. See the sunscreen page.
A history of herpes changes how the procedure is managed before and after.
If you are taking oral isotretinoin or have just finished it, say so in the consultation. The second entry above is about that question.
This is a clinical procedure.

What is not established

We could not include an efficacy trial with an untreated arm. The first entry is a comparison against another laser; the second is a safety trial.
The first entry is the same trial as on the picosecond laser page. Do not count the evidence twice.
The second entry has 10 people. Safety cannot be settled at that size.
We could not include a randomised trial on wrinkles or texture. Both trials above are about acne scars.
Material on non-ablative wavelengths other than 1550 nm (1927 nm and others) is not on this page. 'Non-ablative fractional' does not point at one device.
We have not yet opened the primary Korean regulatory classification, so it stays 'being verified'.

Whether to have it done is a decision to make with a doctor.

What this article relies on

PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16