CO2 laser resurfacing is generally safe when performed by a qualified provider, but it is the most aggressive type of laser skin treatment available, and that intensity comes with real risks. It’s FDA-cleared for skin resurfacing, scar treatment, and removal of certain skin lesions. The fractional version introduced in 2004 significantly improved the safety profile compared to older techniques, though side effects like prolonged redness and pigment changes are still common.
How CO2 Lasers Work on Skin
A CO2 laser emits light at a wavelength that water inside your skin cells absorbs extremely well. That absorption vaporizes the outermost layers of skin, which then regrow from structures deeper in the dermis like sweat glands and hair follicles. Below the vaporized zone, heat causes collagen fibers to contract and tighten, then triggers a remodeling process that continues producing new collagen for months afterward.
There are two approaches. Traditional (fully ablative) CO2 lasers remove every bit of skin in the treatment area, penetrating roughly 400 to 500 micrometers deep. Fractional CO2 lasers split the beam into thousands of tiny columns, vaporizing small dots of tissue while leaving the surrounding skin intact. Those untouched patches act as a reservoir for healing, which is why fractional treatments carry fewer complications and recover faster than full resurfacing.
Common Side Effects
Nearly everyone who gets a fractional CO2 laser treatment will experience noticeable side effects in the first days and weeks. In a retrospective study of patients undergoing various aesthetic procedures, redness affected about 95% of patients and burning sensation affected 92%. Dryness and swelling were each reported in roughly 70% of cases. These are expected parts of healing, not complications, and they typically resolve within the first one to two weeks.
The more concerning number is persistent redness, which lingered in about 46% of patients beyond the normal healing window. Post-inflammatory hyperpigmentation, where treated skin darkens in patches, occurred in nearly 45% of patients. Hyperpigmentation usually fades over several months, but it can be stubborn, particularly in people with darker skin tones.
Serious Complications
Scarring is the complication most people worry about, and the data puts that risk at roughly 3.8%. In clinical series tracking these cases, the most common cause of scarring was post-operative infection. When bacteria or viruses colonize freshly treated skin, healing stalls in a localized area, and the prolonged wound can leave a permanent mark. This is why providers typically prescribe both antibiotic and antiviral medications around the time of treatment.
Herpes simplex virus (the virus behind cold sores) is a particular concern. If you carry the virus, which most adults do, it can reactivate after the trauma of laser resurfacing and spread across the entire treated area. Without antiviral medication taken before and during treatment, this disseminated outbreak can cause significant tissue damage. Anyone with a history of cold sores should be on antiviral prophylaxis, and many providers prescribe it for all patients as a precaution.
Risks for Darker Skin Tones
People with medium to dark skin (often categorized as Fitzpatrick types IV through VI) face higher risks from CO2 lasers. Melanin in darker skin absorbs more of the laser’s energy, which increases the chance of burns, unwanted pigment changes, or both. The risk of post-procedure darkening (hyperpigmentation) or lightening (hypopigmentation) is greater in this group, and hypopigmentation can sometimes be permanent.
Providers can reduce these risks by lowering the laser’s energy level, using a lower treatment density so less skin is affected per session, and prescribing skin-lightening agents like hydroquinone cream before and after treatment. Fractional CO2 delivery was specifically noted to improve outcomes for darker skin compared to full ablative treatment, since leaving intact skin between the laser columns reduces the overall thermal injury to melanin-producing cells. Even with these adjustments, darker-skinned patients should understand they carry a meaningfully higher risk of pigment complications.
Who Should Avoid CO2 Lasers
Active skin infections in the treatment area are a clear reason to postpone. Anyone currently using isotretinoin (a strong acne medication) or who has used it in the recent past is typically advised to wait, because the drug impairs the skin’s ability to heal from the kind of deep injury a CO2 laser creates. Conditions that compromise wound healing, such as uncontrolled diabetes or connective tissue disorders, also increase risk substantially.
If you have a history of abnormal scarring, particularly keloids or hypertrophic scars, the controlled injury from a CO2 laser may trigger the same overactive healing response. And because the laser works by destroying and regrowing skin, any condition or medication that suppresses your immune system can raise the chance of post-procedure infection.
Eye Safety During Treatment
When CO2 lasers are used near the eyes, for crow’s feet or lower eyelid skin, protective eye shields are placed directly over the eyes. Testing of commercially available shields found that metallic shields had the best safety profile, warming slowly and to a lesser degree under laser exposure. Plastic shields showed significant thermal damage during testing, making them unsuitable for CO2 laser procedures around the eyes. If your treatment involves the area around your eyes, you can ask your provider what type of shield they use.
What Recovery Looks Like
Healing from fractional CO2 laser treatment takes about one to two weeks, during which your skin is extremely vulnerable. The treated area needs to stay covered with a bandage that you change twice daily after gently cleaning. You should not apply makeup, over-the-counter ointments, or natural products to the area unless specifically directed by your provider, as these can interfere with healing.
Sun exposure is one of the biggest threats during recovery and for months afterward. Freshly resurfaced skin is highly susceptible to UV damage and pigment changes, so mineral sunscreen with at least SPF 30 or physical coverage with clothing and hats is essential. If you’re on well water, you’ll need to use distilled water for cleaning the treatment site, since well water can introduce bacteria. Showering with well water means keeping the treated area covered.
The strict aftercare protocol is itself a safety consideration. A significant portion of serious complications, including the infections that lead to scarring, stem from inadequate wound care during this healing window rather than from the laser procedure itself. Following post-treatment instructions closely is one of the most effective things you can do to keep your risk low.
Fractional vs. Full Ablative: The Safety Gap
The distinction between fractional and fully ablative CO2 treatment matters enormously for safety. Full ablative resurfacing removes all skin in the treatment zone and carries higher rates of prolonged redness, infection, and pigment changes. It also requires a longer recovery, often several weeks of significant downtime. Fractional treatment, by leaving islands of healthy tissue between the laser columns, gives the skin a built-in healing scaffold. This translates to faster recovery, lower infection rates, and reduced risk of pigment problems.
Most cosmetic CO2 laser treatments performed today use fractional delivery. Full ablative resurfacing is still used for severe scarring or deep wrinkles where maximum results are needed, but the trade-off in side effects is real. If your provider recommends full ablative treatment, it’s worth understanding that you’re accepting a higher risk profile in exchange for more dramatic results.