A CO2 laser is a type of gas laser that produces an invisible beam of infrared light at a wavelength of 10.6 micrometers. It’s one of the most powerful and versatile lasers used in medicine, capable of precisely vaporizing tissue with minimal damage to surrounding areas. CO2 lasers are best known for skin resurfacing, but they’re also used in surgery, dentistry, and treatment of precancerous skin lesions.
How a CO2 Laser Works
Inside the device, a gas mixture of carbon dioxide, nitrogen, and helium is energized by an electrical current. Nitrogen molecules absorb the electrical energy first, then transfer it to the carbon dioxide molecules. When those CO2 molecules release the energy, they emit a concentrated beam of infrared light.
What makes this wavelength so effective on living tissue is that water absorbs it intensely. The beam penetrates only about 12 micrometers into water-containing tissue before its energy is fully absorbed. That extremely shallow penetration means the laser heats a very thin layer of cells so rapidly that the water inside them vaporizes almost instantly, cleanly removing tissue layer by layer. The surrounding tissue receives only a narrow zone of thermal damage, typically 100 to 150 micrometers deep, which is thin enough to heal predictably.
Traditional vs. Fractional CO2 Lasers
There are two broad categories of CO2 laser treatment, and the difference comes down to how the beam hits the skin.
Traditional (non-fractionated) CO2 lasers treat the entire surface area of the targeted zone. Every bit of skin in the treatment field is ablated. This approach delivers dramatic results in a single session but comes with longer healing times and a higher risk of complications.
Fractional CO2 lasers break the beam into thousands of tiny columns, treating only a portion of the skin’s surface while leaving small bridges of untouched tissue between each column. Those intact zones act as reservoirs of healthy cells that speed healing significantly. The trade-off is that fractional treatments typically require more than one session to achieve the same degree of improvement, but downtime and complication rates drop substantially.
Within the fractional category, different settings control how deep the laser penetrates. Superficial modes use a wider spot size (around 1.3 mm) to treat fine lines and sun damage at the skin’s surface. Deep modes focus energy into a tiny 0.12 mm spot and can ablate tissue up to 2 mm deep, reaching scars and deep wrinkles. Some systems combine both in a single session.
Skin Conditions Treated With CO2 Lasers
CO2 laser resurfacing is most commonly used for photoaging, the cumulative sun damage that shows up as wrinkles, rough texture, and uneven pigmentation. It’s also effective for acne scars, surgical scars, and traumatic scars, where the laser remodels the damaged collagen beneath the skin’s surface.
Beyond cosmetic concerns, CO2 lasers treat precancerous growths like actinic keratoses and certain early-stage skin cancers, including squamous cell carcinoma and basal cell carcinoma. Dermatologists also use them to remove individual lesions like warts, skin tags, and vascular growths.
Uses Outside of Dermatology
The precision of a CO2 laser makes it useful well beyond skin resurfacing. In dentistry, it serves as an alternative to the scalpel for soft tissue procedures like removing excess gum tissue or releasing a tight frenulum (the small band of tissue under the tongue or lip). The laser cauterizes as it cuts, which reduces bleeding and often eliminates the need for stitches.
In ear, nose, and throat surgery, CO2 lasers are used for procedures on the vocal cords, tongue, and airway. Gynecologists use them to treat cervical lesions. In each of these fields, the laser’s ability to make thin, controlled cuts with a predictable zone of thermal effect gives it an advantage in delicate areas where preserving surrounding tissue matters.
What Recovery Looks Like
After a fractional CO2 laser treatment, healing generally takes one to two weeks. During the first several days, the treated skin typically looks red or darkened and develops a crust. That crust gradually falls away over the one- to two-week window as new skin forms underneath.
Redness can persist well beyond the initial healing phase, sometimes lasting weeks to months depending on the aggressiveness of the treatment and your skin type. With traditional full-surface ablation, recovery takes longer than with fractional treatments, and the redness tends to be more pronounced and prolonged.
Risks and Side Effects
The most common side effect is prolonged redness, which is expected and temporary. More serious complications are uncommon but worth knowing about. Scarring occurs in roughly 4% of cases. Older, non-fractionated CO2 lasers caused permanent lightening of the skin (hypopigmentation) in up to 19% of patients, but this has become rare with modern fractional systems.
Infection is another risk. CO2 laser treatment can reactivate the herpes simplex virus in people who carry it, potentially causing a cold sore outbreak in the treated area. To prevent this, patients are typically given an antiviral medication starting the day before the procedure and continuing for 10 to 14 days afterward.
Who Should Be Cautious
Skin tone plays a meaningful role in how safely CO2 lasers can be used. People with darker skin (Fitzpatrick types III through VI) are more prone to post-inflammatory hyperpigmentation, a temporary darkening of the treated area that can last months. Experts recommend that all patients, regardless of skin tone, take steps to minimize this risk before treatment, but the concern is highest for those with more melanin in their skin.
Absolute contraindications include active cold sore outbreaks in the treatment area, recent sunburn or heavy sun exposure in the weeks before the procedure, and pregnancy or breastfeeding. Active skin infections or a history of abnormal scarring (keloids) also raise red flags that need to be addressed before proceeding.