Microneedling for Acne Scars: Which Scars, and Why

Microneedling is studied mainly for atrophic acne scars, and the response depends on shape. Rolling and shallow boxcar scars respond moderately in the dermatology literature. Ice pick scars and deep boxcar scars respond poorly. Active acne rules the procedure out entirely. Scar work belongs with a dermatologist, not a home device.

That ranking is not a marketing position. It comes from how each scar is built, and how deep it runs. This article sets out what the published literature says about scar type and microneedling. It also marks the line for anyone treating skin at home.

Which acne scars respond to microneedling?

Rolling and shallow boxcar scars respond moderately. Ice pick and deep boxcar scars respond poorly. Tam and colleagues graded every treatment against every atrophic scar subtype. Their 2022 review ran in Clinical, Cosmetic and Investigational Dermatology. Microneedling scored moderate for rolling and shallow boxcar scars. It scored poor for ice pick and deep boxcar scars.

The reason is geometry. Every treatment reaches a set depth and works by a set mechanism. Every scar has its own depth and its own cause. Match the two and the treatment acts on the actual defect. Miss, and it acts on tissue that was never the problem.

Scale matters here too. The same review reports that more than 80 percent of acne scars are atrophic. Within that group, ice pick scars are the most common at roughly 60 percent. Boxcar scars follow at roughly 25 percent, and rolling scars at roughly 15 percent. The most common scar type is the one microneedling handles worst.

The three atrophic scar types, side by side

Surface width separates them first. Depth separates them second. The widths below follow the classification by Jacob, Dover and Kaminer. It was published in the Journal of the American Academy of Dermatology in 2001. Clinical trials still use that system.

Scar type	Width at the surface	Where it reaches	Microneedling response	Best-rated option in the 2022 review
Ice pick	Under 2 mm	Lower dermis or subcutis	Poor	Chemical peel
Boxcar, shallow	1 to 4 mm	Upper dermis	Moderate	Several rated moderate, none rated good
Boxcar, deep	1 to 4 mm	Lower dermis	Poor	Punch excision
Rolling	4 mm or wider	Upper dermis, tethered from below	Moderate	Subcision, and dermal filler

Most faces carry more than one type at once. Our guide to telling ice pick, boxcar and rolling apart covers the daylight identification test. It also covers the difference between a scar and a flat mark.

Why ice pick scars are the hardest to treat

Ice pick scars run deeper than the other two types, and the opening at the surface is tiny. Resurfacing the top of the skin removes far less than the scar extends downward.

Depth has now been measured directly. Bansal and colleagues examined 49 biopsies of atrophic acne scars. Their 2026 histopathology study ran in the Indian Journal of Dermatology, Venereology and Leprology. Mean vertical depth was 1933.4 µm for ice pick scars. Boxcar scars measured 1327.88 µm and rolling scars 1357.14 µm. The gap between ice pick and boxcar scars reached significance at p=0.02.

Read those numbers in millimetres. An ice pick scar averages about 1.9 mm deep. The authors concluded that an energy device should reach roughly 1933.4 µm. That depth would address all atrophic scar types. That is a clinic setting on a clinic device, chosen by someone who assessed the skin first.

The study was conducted in skin of color. Its authors name the small sample size as a limitation.

Why rolling scars need the tether released first

Rolling scars are not missing much tissue. Fibrous bands tether the surface down to the layer beneath. The skin above is pulled rather than absent.

The 2022 review is direct about what follows. Chemical peels, microneedling and fillers can reduce how a rolling scar looks. None of them addresses the tether. Subcision is described as the only approach delivering the mechanical force needed to break those bands.

The same review reports the opposite result for the other two types. Subcision alone is ineffective for boxcar scars and almost entirely ineffective for ice pick scars. Neither carries the tethering that defines a rolling scar.

Why boxcar scars split into two different problems

A boxcar scar has vertical walls and a flat floor. Depth decides which treatment reaches it. The shallow and deep versions behave like separate conditions.

Shallow boxcar scars sit in the upper dermis. The review rates them moderate for microneedling, dermabrasion, microdermabrasion, subcision, chemical peel and filler. Deep boxcar scars reach the lower dermis, and punch excision is rated the strongest option for them. Microneedling drops to poor.

What the microneedling studies actually measured

The trials are real, the effects are modest, and the protocols are clinical. Three findings are worth stating precisely.

• Sitohang and colleagues reviewed nine randomised controlled trials. Their 2021 systematic review ran in the International Wound Journal. Microneedling was efficacious for atrophic acne scars as monotherapy or in combination. No serious adverse effects were reported in any of the studies.
• An open-label study in the Journal of Clinical and Aesthetic Dermatology tested an automated device. Subjects had four sessions, 30 days apart. Scars improved by 0.91 of a grade on the Goodman and Baron scale. The confidence interval ran 0.78 to 1.05, at p<0.001. That was measured three months after the last session. Of those responding, 33 of 43 subjects reported visible improvement.
• Iriarte and colleagues list the atrophic scar trials in their review of microneedling applications. It also ran in Clinical, Cosmetic and Investigational Dermatology. Needle depth in those studies is 1.5 mm. Sessions run four to six times, at two to four week intervals.

Under one grade of average improvement, after four professional sessions, is the honest shape of the evidence. It is a real effect. It is not erasure.

Can you microneedle over active acne?

No. This is the firmest rule in the article, and it is not ours. The American Academy of Dermatology delays treatment until certain pimples clear. That means pimples that are painful, contain pus, or run deep.

The logic is straightforward. Needling drags inflammation and bacteria sideways through skin that is already inflamed. Deep, prolonged inflammation is how atrophic scars form in the first place. Treating over active acne risks producing the thing you were trying to correct.

Contraindications you must clear first

The AAD lists conditions where microneedling should not be performed at all. Do not proceed if you heal slowly or poorly. The same applies to a keloid scar, now or in the past. It also applies to a weakened immune system, from a condition or a medication. Skin cancer treatment in the area rules it out, as does radiation treatment.

Other conditions require a delay. Those include a tan or recent sun exposure, any skin infection, and painful, pus-filled or deep pimples. For isotretinoin, the AAD states that at least one month must have passed since the last pill. Our contraindications guide covers the full list.

The AAD also recommends seeing a board-certified dermatologist for microneedling. It names at-home needling as a practice carrying infection and technique risk. We sell a home device and we are still going to print that.

Start shallow

Anyone using a home device starts at the shallowest setting, on the most forgiving cartridge. Test one small area first. Increase nothing until you have watched how your skin responds over a full week. One pass, once a week, is the ceiling and not the starting point. Aftercare matters as much as the session, and the side effects guide separates normal from not.

Does a home device treat acne scars?

Ours does not, and we will not claim otherwise. The re:tones Tap Pen is a cosmetic device. It does not diagnose, treat, cure or prevent any condition. Acne scarring is a clinical problem.

The specification makes the limit concrete. The depth collar runs from 0.5 mm to 1.5 mm. An ice pick scar averages about 1.9 mm deep in the histology above. The deepest setting on the collar stops short of where the most common atrophic scar type ends. Depth is one variable of several, and it already fails to line up.

If scarring is your main concern, the correct first spend is a dermatologist consultation. A single visit that names your scar types saves a year of buying the wrong thing. Our depth guide explains what each setting reaches, and why we cap the range where we do.

What a home device is actually for

The argument we do make has nothing to do with scars. The outer layer of your skin is a barrier. Its job is to keep things out, and it does not care what your serum cost. Most of what you pat on stays on top, dries, and ends up on your pillow.

Microneedling opens temporary channels through that outer layer. The Tap Pen releases the ampoule at the moment the tip meets skin. The formula and the road arrive together. That is a delivery mechanism for ordinary concerns like tone and texture. Our science page covers the barrier and what crosses it. Why your serum is not absorbing covers the problem it was built for.

We make no promise about your result. We tell you the mechanism and the specification. We also tell you where the mechanism stops.

Frequently asked questions

Does microneedling work on acne scars?

Clinical microneedling has published evidence for atrophic acne scars. A 2021 systematic review of nine randomised controlled trials found it efficacious alone or combined with other treatments. Average gains in one device trial were under one grade after four professional sessions. That is meaningful improvement, not removal, and it happens in a clinic.

Which acne scars does microneedling not help?

Ice pick and deep boxcar scars, both rated poor in the 2022 review. Both reach the lower dermis. Neither responds well to a treatment working from the surface downward. Ice pick scars are also the most common atrophic type, at roughly 60 percent. Clinicians usually reach for other techniques entirely.

How many microneedling sessions do acne scars need?

Published protocols run four to six sessions, spaced two to four weeks apart. The device trial cited above used four sessions 30 days apart. Results were assessed three months after the last one. Scar work is a series rather than an appointment. The assessment gap exists because collagen changes take months.

Can microneedling make acne worse?

It can, over active lesions. Needling through inflamed skin can spread inflammation and bacteria into surrounding tissue. The AAD delays treatment until painful, pus-filled or deep pimples have cleared. Breakouts after a session on clear skin are a separate question. Our article on microneedling and purging covers it.

How long after isotretinoin can you microneedle?

The American Academy of Dermatology sets a minimum of one month. That is one month since your last isotretinoin pill. Practice varies, and some clinicians wait considerably longer. This is a question for the prescriber who knows your course and your healing. It is not a rule to settle online.

Is microneedling safe for deeper skin tones?

The Iriarte review describes microneedling as a viable resurfacing option for skin of color. The 2026 depth study was also conducted in skin of color. Resurfacing procedures generally carry pigment-change risk in deeper tones. That is one reason a clinician plans scar treatment around skin type.

Do at-home dermarollers treat acne scars?

No home device should be sold as a scar treatment, rollers included. The published scar trials use 1.5 mm depths in clinical settings, with trained operators. The AAD names at-home needling as carrying infection and technique risk. Rollers and pens differ mechanically, and neither changes that answer.

What is the difference between a scar and a dark mark?

A scar changes the structure of the skin, so the surface is not level. A mark is color change on intact skin, and it fades over months with sun protection. People treat one as the other for years. Fading dark spots is a different approach entirely.

The short version

Scar type decides the treatment. Rolling and shallow boxcar scars respond moderately to microneedling in the literature. Ice pick and deep boxcar scars do not. Rolling scars need the tether cut. Active acne is a hard stop. A home device, ours included, is a delivery tool for ordinary skincare rather than a scar procedure.

Last updated: August 19, 2026. Reviewed against the cited dermatology literature. This article is general information, not medical advice. Speak to a board-certified dermatologist about acne scarring.