TL;DR
Boxcar scars are sharp-walled, flat-floored depressions that resemble shallow craters. Unlike ice picks, the floor is wide enough for resurfacing energy to work. The evidence ranks fractional ablative laser and radiofrequency microneedling at the top, with subcision useful for the deeper boxcars and TCA cross reserved for the narrow ones. Topicals support pigment and prevent new acne but don’t reshape the wall.
A patient last month brought me a list of nine products she’d tried for her boxcar scars. The list was thoughtful. The list was also entirely topical. None of those products were ever going to reshape a vertical scar wall, and nobody had told her that out loud. Most boxcar advice on the internet stops short of the in-clinic conversation. So let’s have it.
How to spot a boxcar scar
Boxcars are roughly round or oval, 1.5 to 4 millimeters wide, with steep walls and a flat base. They look like someone pressed a small punch into the skin and lifted it out cleanly. Run a raking light across the cheek and they read as sharp dark rims around a lit floor. Shallow boxcars sit in the first 0.5 millimeter of dermis. Deep boxcars go past 0.5 millimeters and need different treatment.
Most people have a mix of scar types. Telling them apart matters because the treatment ranking changes. Atrophic acne scars covers the full taxonomy if you’re still sorting.
Why boxcars hold their shape
Boxcars form when an inflammatory acne lesion destroys collagen in a defined column, then heals with vertical walls of relatively normal dermis on either side. There’s no tethering to release, which is why subcision alone often disappoints on shallow boxcars. The structural problem is missing tissue inside steep walls. Either you resurface the rim down to the floor, or you stimulate the floor up to the rim. The good news: the walls cooperate with energy-based devices in a way ice picks don’t.
The in-clinic options, ranked
Fractional ablative CO2 laser is the strongest single device for boxcar scars in published trials. The laser drills thousands of microscopic columns of controlled injury, the dermis remodels, and the rim softens into the floor over three to six months. Expect 50 to 70 percent improvement after one to three sessions. Downtime is real, typically 7 to 10 days of pink, raw skin.
Radiofrequency microneedling is the close second and often the more practical pick for darker skin tones, where ablative laser carries higher pigment risk. The device drives insulated needles into the dermis and delivers heat at depth without burning the surface. Less downtime, 2 to 4 days of redness, and three to four sessions for visible change.
Subcision is the right first step for deeper boxcars with any tethering. A blunt cannula releases the fibrous bands pulling the floor down, then the area is treated with laser or RF six weeks later. Rolling acne scars covers subcision in more detail.
TCA cross at 70 to 100 percent works on small, narrow boxcars under 2 millimeters wide. It’s less effective on wide ones, where the acid can’t deposit evenly across the floor.
Filler is a temporary smoothing tool. Hyaluronic acid filler in the dermal floor lifts the depression for 12 to 18 months. Useful before a wedding or event, useful as a bridge while laser remodeling builds. Not a permanent answer.
What topicals genuinely add
I’d keep this short because the supplement-side is over-marketed. Tretinoin 0.025 to 0.05 percent nightly supports collagen remodeling and prevents the new acne that would create more boxcars. Daily SPF 30 or higher keeps the rim from darkening and reading deeper than it is. Azelaic acid 10 to 15 percent holds post-inflammatory pigment. None of those reshape a wall. They make the in-clinic work read better in photos.
For pigment overlapping the scar, tranexamic acid is genuinely useful.
What doesn’t work
Snail mucin alone. Bakuchiol. Vitamin C as a scar-filler claim. At-home dermarollers at 0.5 millimeter depth. These keep the surface healthy and have no mechanism to lift a scar floor. The marketing implies otherwise because the upside on resurfacing devices requires a clinic.
One more honest caveat. Microneedling pens marketed for home use don’t reach the dermal depth that matters for boxcars, typically 1.5 to 2 millimeters. The medical-grade work is at that depth with sterile field and a trained operator. The home version polishes the surface and feels productive.
When to see a dermatologist
Any boxcar that bothers you in raking light or photos. Boxcar fields covering the cheeks or temples. New boxcars forming because acne is still active, which is the more urgent issue. Pigment that hasn’t faded inside the scar after 12 months. A board-certified dermatologist or fellowship-trained cosmetic dermatologist is the right address. Ask specifically about RF microneedling and fractional laser experience with your skin tone. The American Academy of Dermatology notes that atrophic scars, including boxcars, affect up to 80 percent of people with moderate to severe inflammatory acne; the earlier you start the in-clinic work, the better the long-term outcome.
FAQ
How many laser sessions will I need for boxcars? Typically one to three for fractional CO2, three to four for RF microneedling. Depth and number of scars matter.
Is RF microneedling safer than laser for skin of color? The published data favors RF microneedling for Fitzpatrick IV to VI skin because there’s less pigment risk. Confirm with a provider experienced in your skin tone.
Does subcision work for shallow boxcars? Rarely on its own. Shallow boxcars usually aren’t tethered. Save subcision for deeper boxcars or rolling scars.
How long does filler last in a boxcar? 12 to 18 months for hyaluronic acid filler in the dermal floor. It’s a bridge, not a fix.
Can topicals shrink a boxcar over time? They can soften the rim slightly with long-term retinoid use, not enough to call it shrinkage. The wall remains.
Sources: American Academy of Dermatology, Acne Scar Treatment (2024); PubMed, Journal of the American Academy of Dermatology (2018); PubMed Central, Indian Dermatology Online Journal (2017). The acne scars tag collects more.