Carboxytherapy is a minimally invasive cosmetic procedure in which small amounts of carbon dioxide gas are injected just beneath the skin to improve circulation, stimulate collagen production, and break down localized fat. The technique has been around since 1932, when practitioners at the Royat thermal spa in France noticed that bathing in CO2-enriched pools accelerated wound healing. Today it’s used primarily for aesthetic concerns like cellulite, stretch marks, dark under-eye circles, fine lines, and scars.
How Carboxytherapy Works
The core idea is surprisingly simple. When carbon dioxide gas is injected into the skin or the fat layer just below it, your body interprets the sudden rise in CO2 as a sign that the area needs more oxygen. Blood vessels in the treated zone dilate, rushing oxygen-rich blood to the tissue. This process, known as the Bohr effect, is the same mechanism your body uses during exercise to direct oxygen toward working muscles.
That surge in blood flow does several things at once. It delivers fresh nutrients to skin cells, encourages the formation of new collagen and elastin, and helps break apart small pockets of fat. In stretch marks specifically, clinical measurements show the effect on skin structure is real: one study published in the Journal of Clinical and Aesthetic Dermatology found that epidermal thickness increased from an average of about 45 micrometers before treatment to roughly 67 micrometers four months later, a nearly 50% gain.
What It Treats
Carboxytherapy is used across a wide range of cosmetic concerns. The most common applications include:
- Cellulite and localized fat: Injections into the fat layer can reduce circumference measurements. In a study of 111 patients treated for abdominal cellulite, waist circumference decreased by 1.1 to 2.6 cm on average, corresponding to roughly 0.9 to 1.6 kg of fat loss. Results are modest, not dramatic.
- Stretch marks: A trial of 15 women aged 22 to 40 found that three weekly sessions significantly improved both skin elasticity and the visible appearance of stretch marks. In a separate comparison trial, patient satisfaction with carboxytherapy matched that of radiofrequency treatments and exceeded platelet-rich plasma (PRP) therapy.
- Dark circles and under-eye wrinkles: In a trial of 90 patients with moderate to severe periorbital wrinkles or dark circles, weekly CO2 injections over seven weeks produced noticeable improvements in both fine lines and pigmentation. That said, the results were more modest than those achieved with intense pulsed light or fractional laser treatments.
- Scars: For atrophic (indented) scars not caused by acne, a comparative trial of 40 patients found that carboxytherapy produced better clinical improvement and higher patient satisfaction than PRP.
- Body contouring: The treatment is also applied to the double chin, neck, inner thighs, and upper arms for mild skin tightening, sometimes as a follow-up to liposuction.
What a Session Feels Like
A practitioner uses a small needle connected to a device that controls the flow rate and volume of CO2 gas. The injection depth varies depending on the goal. For skin rejuvenation and scar treatment, the gas goes into the dermis (the upper skin layer). For cellulite and fat reduction, the needle goes deeper into the subcutaneous fat layer, typically at a 30 to 45 degree angle.
Most people describe the sensation as a mild pressure or stinging at the injection site. When treating cellulite or fat, the expanding gas can create a feeling similar to the squeeze of a blood pressure cuff. Some people notice a crackling sensation under the skin as the gas spreads, which is temporary and harmless. The gas is fully absorbed by the body within minutes.
Sessions typically last 15 to 30 minutes depending on the size of the area being treated. Most protocols call for weekly sessions, with a total course ranging from about 4 to 10 treatments depending on the condition. Stretch marks and scars generally need more sessions than dark circles or fine lines.
Recovery and Downtime
There is essentially no downtime. You can return to your normal routine immediately after treatment. The one restriction: if you’re being treated for cellulite or fat reduction, you should avoid swimming and soaking in a bath for 24 hours.
Treated areas typically feel warm and tingly for up to 24 hours as circulation increases in the area. Some people notice mild redness or small bruises at the injection sites, which usually resolve within a day or two. A brief, odd sensation under the skin is common right after treatment but passes quickly.
How It Compares to Other Treatments
Carboxytherapy occupies a middle ground in aesthetic medicine. It’s less invasive than laser treatments and surgery, but the results are also generally more subtle. In head-to-head comparisons, fractional CO2 laser therapy consistently outperformed carboxytherapy for wrinkles, with patients reporting notably better satisfaction after laser sessions. For dark circle pigmentation, PRP reduced hyperpigmentation by an average of 46.6% compared to just 14.3% for carboxytherapy in a split-face trial of 23 patients.
Where carboxytherapy holds its own is in stretch marks and non-acne scars, where it performed as well as or better than PRP and radiofrequency treatments. It also carries fewer risks than laser procedures, making it an option for people who want gradual improvement without the recovery period that comes with more aggressive treatments.
Limitations and Realistic Expectations
The evidence base for carboxytherapy is growing but still limited. Many studies involve small groups of patients, and some results, like the circumference reduction seen in cellulite trials, haven’t always reached statistical significance. A randomized trial of 16 adults who received five weekly CO2 infusions for abdominal fat found that circumference decreased, but the change wasn’t statistically meaningful.
Carboxytherapy is not a weight-loss tool or a replacement for surgical procedures. The fat reduction it produces is measured in centimeters, not dress sizes. For wrinkles and pigmentation, it often takes the full course of treatments before changes become visible, and maintenance sessions may be needed to sustain results. People with realistic expectations for gradual, mild to moderate improvement tend to be the most satisfied.