A CO2 fractional laser is a skin resurfacing device that uses carbon dioxide light energy to create thousands of tiny, evenly spaced channels in the skin, triggering the body’s natural healing response and new collagen production. Unlike older CO2 lasers that removed the entire surface of treated skin, the fractional approach treats only a portion of the skin at a time, leaving healthy tissue between each channel to speed up recovery and reduce the risk of complications.
How It Works
The laser emits light at a wavelength of 10,600 nanometers, which is strongly absorbed by water in skin cells. When the beam hits the skin, that water absorbs the energy almost instantly, vaporizing thin columns of tissue sometimes called micro-tunnels or microthermal zones. Each column is microscopic in width, and they’re spaced apart in a grid pattern so that untouched skin surrounds every point of damage.
This is the key insight behind fractional technology: by leaving bridges of healthy tissue intact, the skin can rebuild itself from the edges of each channel inward. The controlled heat also reaches the deeper layers of the skin, where it breaks down old, fragmented collagen fibers and stimulates fresh collagen production. Research shows that the building blocks of new collagen (types I and III) peak around three weeks after treatment and continue forming for up to six months. That means your skin keeps improving well after the surface has healed.
Beyond resurfacing, the micro-tunnels the laser creates have become a tool for drug delivery. Because the channels temporarily bypass the skin’s outer barrier, topical medications or serums applied right after treatment can penetrate much deeper than they normally would.
Fractional vs. Traditional CO2 Lasers
Traditional, non-fractional CO2 lasers treat the entire surface of the targeted area. They’re powerful, but that comes at a cost: difficult wound healing, a meaningful risk of scarring, and the possibility of permanent lightening of the skin. These side effects made the original devices a serious commitment with significant tradeoffs.
Fractional CO2 lasers solved most of those problems by distributing the same type of energy across a fraction of the skin’s surface. The result is fewer complications, faster healing, and far less risk of permanent pigment changes. The trade-off is that you may need more than one session to achieve the same depth of improvement a single fully ablative treatment might produce. For most people, that exchange is well worth it.
What It Treats
Fractional CO2 lasers are used for a broad range of skin concerns, with the best results typically seen in conditions that involve texture changes or collagen loss:
- Acne scars. Atrophic (indented) acne scars are one of the most common reasons people seek this treatment. The laser removes damaged surface tissue and triggers collagen rebuilding underneath, gradually filling in depressed scars over several months.
- Wrinkles and fine lines. Both sun-related and age-related wrinkles respond to fractional CO2 resurfacing. Deeper wrinkles and skin laxity tend to respond better to the ablative approach than to gentler, non-ablative lasers.
- Sun damage and precancerous spots. Rough, scaly patches caused by years of sun exposure can be treated effectively.
- Uneven skin texture and tone. General dullness, enlarged pores, and rough texture from photoaging all improve with resurfacing.
- Surgical or traumatic scars. Scar revision with fractional CO2 can soften and flatten raised or irregular scars over time.
How It Compares to Erbium YAG Lasers
The other major fractional ablative laser uses erbium YAG technology. The key difference is thermal effect. CO2 lasers generate more residual heat in surrounding tissue, which makes them more aggressive but also more effective at stimulating deep collagen remodeling. Erbium YAG lasers produce less thermal damage, leading to faster surface healing and a more controllable, gentler resurfacing. For milder concerns or patients who need minimal downtime, erbium may be a better fit. For deeper scars or more severe sun damage, CO2 generally delivers stronger results.
What the Procedure Feels Like
Before treatment, a topical numbing cream is applied under a covering and left on for 45 to 60 minutes. Some practitioners use additional local anesthesia for more aggressive sessions. The procedure itself typically takes 15 to 45 minutes depending on the area being treated. Most people describe it as a hot, prickling sensation, though the numbing cream takes the edge off significantly.
The laser settings, including beam width, depth, and spacing of the micro-tunnels, are adjusted based on the specific concern being treated and the area of the face or body involved. Thicker skin on the cheeks can handle more aggressive settings than delicate skin around the eyes.
Recovery and Downtime
Immediately after treatment, the skin looks red, swollen, and feels sunburned. Over the first few days, you can expect oozing and crusting as the skin’s surface begins to seal over the microscopic channels. Most people see the surface re-form within five to seven days, though redness can persist for several weeks to a few months depending on treatment intensity.
Collagen remodeling continues beneath the surface for up to six months after a session. This means the visible improvement you see at one month is not the final result. Skin continues to tighten, smooth out, and build structure over that longer timeline. Most people look socially presentable within one to two weeks, though makeup may be needed to cover lingering pinkness.
How Many Sessions You’ll Need
The number of sessions depends on what you’re treating and how aggressively each session is performed. For moderate acne scars, studies have evaluated protocols using two or more sessions. Research comparing one-month and three-month intervals between sessions found similar improvement regardless of spacing, so your provider has flexibility in scheduling. Mild concerns like fine lines or texture might improve with a single session, while deep scarring or significant sun damage often benefits from two to four treatments spread over several months.
Risks and Side Effects
The most common significant side effect is post-inflammatory hyperpigmentation, or PIH, where the treated skin develops dark patches during healing. This happens because the thermal damage triggers an overproduction of pigment as part of the inflammatory response. PIH is temporary in most cases, typically appearing about a month after treatment and resolving over the following three to four months.
The risk is directly tied to natural skin tone. In one study of patients with moderately dark skin (Fitzpatrick type IV), 68% developed PIH. It was not preventable by choice of laser or pre-treatment skin care regimen, though it responded well to treatment once it appeared. For people with darker skin tones, fractional CO2 carries a notably higher risk of pigment changes, and the decision to proceed requires careful consideration of alternatives.
Other possible side effects include prolonged redness, infection (the skin’s barrier is temporarily compromised), and, rarely, scarring. Active bacterial or viral skin infections in the treatment area are a contraindication, meaning the procedure should not be done until those are resolved. Providers typically prescribe antiviral medication beforehand to prevent reactivation of cold sores, which can spread rapidly on freshly lasered skin.
Who Gets the Best Results
People with lighter skin tones, moderate to severe acne scarring, or significant sun damage and wrinkles tend to see the most dramatic improvements. The fractional approach has made CO2 resurfacing accessible to a wider range of patients than the original fully ablative lasers allowed, but skin tone remains the single biggest factor in predicting side effects. If you have naturally dark or olive skin, a thorough conversation about PIH risk and alternative treatments (like erbium YAG or non-ablative fractional lasers) is an important step before committing.