Carboxytherapy is a minimally invasive cosmetic and medical procedure in which small amounts of carbon dioxide gas are injected just beneath the skin through a fine needle. The idea sounds counterintuitive: CO₂ is the gas your body works hard to expel, yet deliberately introducing it into tissue triggers a cascade of local responses, from increased blood flow and oxygen delivery to new collagen production. Practitioners use it for everything from under-eye dark circles to cellulite, stretch marks, and even hair loss, though the strength of the evidence varies considerably by application.
How Carbon Dioxide Triggers a Healing Response
The core mechanism behind carboxytherapy rests on something called the Bohr effect. When CO₂ is injected into tissue, the local concentration of the gas rises sharply. Hemoglobin in nearby red blood cells responds by releasing more oxygen into the surrounding tissue than it normally would, because hemoglobin’s grip on oxygen loosens in the presence of elevated CO₂.1Journal of Cranio-Maxillofacial Surgery. Carboxytherapy, subcutaneous injections of carbon dioxide in the management of infraorbital dark circles: A reliable and effective procedure In practical terms, the injected area gets a temporary surge of oxygen it would not otherwise receive.2PubMed Central. Topical Carboxytherapy for Skin Rejuvenation
That oxygen boost is just the start. The body interprets the sudden presence of CO₂ under the skin as a mild injury, and it responds accordingly. Blood vessels in the area dilate, improving circulation to the treated zone. Over repeated sessions, the tissue also forms new small blood vessels, a process researchers have confirmed by observing increased vessel numbers and higher expression of growth-factor genes in treated adipose tissue.3PubMed. Carboxytherapy-Induced Fat loss is Associated with VEGF-Mediated Vascularization Better blood flow means better nutrient delivery, faster waste removal, and a tissue environment primed for repair.
A third key effect involves the skin’s structural scaffolding. Studies using tissue biopsies after carboxytherapy sessions have shown increased collagen and elastic fiber production, along with measurably thicker epidermis and dermis layers.4PubMed Central. Pathological and Immunohistochemical Assessment of Aging of the Abdominal Skin Treated with Carboxytherapy: A Randomized, Split-body Trial Collagen gives skin its firmness, and elastic fibers give it the ability to bounce back, so stimulating both is central to the rejuvenation claims surrounding the procedure.5PubMed. Effects of carboxytherapy on skin laxity
What Happens to Fat Cells
When carboxytherapy is aimed at fat reduction rather than skin quality, a different aspect of the same process comes into play. The injected CO₂ appears to physically damage fat cells. Histological studies have observed adipocytes with fractured cell walls after treatment, releasing their stored triglycerides into the surrounding space, where the body can clear them out. Researchers have also noted a shrinkage and reduction in density of fat cells in treated areas.3PubMed. Carboxytherapy-Induced Fat loss is Associated with VEGF-Mediated Vascularization This mechanical disruption of fat, combined with the improved local blood flow that helps carry away the debris, is what underlies the use of carboxytherapy for localized fat deposits and cellulite.6Journal of the Egyptian Women’s Dermatologic Society. Role of carboxytherapy in localized lipolysis: a clinical and radiological study
It is worth keeping expectations in check here. The fat reduction from carboxytherapy is localized and modest. Nobody is losing significant body weight from the procedure. The measurable changes in clinical trials are typically in the range of a centimeter or two off a thigh circumference, not the kind of dramatic reshaping people associate with liposuction. It is better understood as a contouring or smoothing tool than a weight-loss method.
Cellulite Treatment
Cellulite is one of the most studied applications of carboxytherapy. The lumpy, dimpled appearance of cellulite comes from a combination of fat deposits pushing against connective tissue bands beneath the skin, and carboxytherapy targets several parts of that problem at once: it disrupts fat cells, stimulates collagen remodeling in the connective tissue, and improves circulation.
A pilot study in healthy women found that carboxytherapy reduced cellulite severity from grade III to grade II in the buttocks and posterior thighs, with ultrasound imaging confirming improved organization of the fibrous and adipose tissue layers underneath.7PubMed Central. Effectiveness of carboxytherapy in the treatment of cellulite in healthy women: a pilot study A separate comparative trial pitting carboxytherapy against mesolipolysis (a technique that injects fat-dissolving compounds) found that both treatments significantly reduced thigh circumference and cellulite grading, with no meaningful difference between the two.8PubMed. Evaluation and efficacy of carbon dioxide therapy (carboxytherapy) versus mesolipolysis in the treatment of cellulite A larger clinical audit of 57 women who received localized thigh treatments reported circumference reductions of roughly one to two centimeters per thigh across different age groups.9PubMed Central. Carbon dioxide therapy in the treatment of cellulite: an audit of clinical practice
These results are consistent across studies, which gives cellulite some of the strongest evidence among carboxytherapy applications, though most trials remain small and lack long-term follow-up data on how long the improvements last.
Under-Eye Dark Circles
Dark circles under the eyes are another popular target. In many people, these circles result partly from sluggish blood flow beneath very thin periorbital skin, which makes the underlying blood vessels more visible. Because carboxytherapy pushes oxygen into tissue and dilates local blood vessels, the logic of using it here is straightforward.
Clinical results back this up. One trial measured both physician and patient scores of dark-circle severity before and after treatment and found that scores dropped by roughly half, with no major side effects reported.10PubMed. Evaluation of the effects of carboxytherapy in the treatment of periorbital dark circles Another study measured the vascular and pigmentary components of under-eye circles separately and found that carboxytherapy significantly reduced the vascular component, with over 80% of participants showing improvement in the tear-trough area when carboxytherapy was combined with a chemical peel.11Clinical, Cosmetic and Investigational Dermatology. The Impact of Carboxytherapy and Treatments Combining Carboxytherapy and Selected Chemical Peels on Vascular and Pigmentary Components of the Dark Circles Patients have also reported reductions in fine lines and wrinkles around the eyes alongside the pigmentation improvement.12PubMed. Periorbital area rejuvenation using carbon dioxide therapy
One nuance: dark circles have multiple causes, including genetics, bone structure, and true hyperpigmentation from melanin deposits. Carboxytherapy works best on the vascular component, meaning the circles caused by poor circulation and thin skin. If your dark circles are primarily structural (from a deep tear trough or hollowing) or heavily pigmented from melanin, carboxytherapy alone is unlikely to eliminate them.
Stretch Marks and Skin Rejuvenation
Stretch marks, known clinically as striae distensae, form when the skin stretches faster than its collagen network can keep up with, leaving scarred bands of thinned, disorganized tissue. Carboxytherapy addresses this by stimulating new collagen deposition and reorganizing existing collagen fibers in the stretched area. A comparative study found that stretch marks improved significantly after carboxytherapy, with histological analysis showing that the epidermis thickened from about 45 micrometers to about 67 micrometers after treatment, and collagen bundles became more compact and better organized.13Journal of Clinical and Aesthetic Dermatology. Carboxytherapy versus its Combination with Fractional CO2 Laser for the Treatment of Striae Distensae: An Objective, Right-to-left, Comparative Study
Interestingly, the same study compared carboxytherapy alone against carboxytherapy combined with fractional CO₂ laser and found no statistically significant difference between the two sides, which suggests the CO₂ injections were doing most of the work. A separate head-to-head trial comparing carboxytherapy with platelet-rich plasma injections for stretch marks found both methods equally effective, with similar patient satisfaction scores.14PubMed. Clinical and immunohistochemical comparative study of the efficacy of carboxytherapy vs platelet-rich plasma in treatment of stretch marks Newer, redder stretch marks (striae rubrae) tend to respond better than older, white ones (striae alba), which is a pattern consistent across most scar-treatment modalities.
For general skin rejuvenation beyond stretch marks, the collagen and elastic fiber stimulation documented in biopsy studies makes carboxytherapy a candidate for mild skin laxity and fine lines. However, when researchers compared carboxytherapy head-to-head with radiofrequency for skin rejuvenation, they found that while both stimulated collagen remodeling, radiofrequency produced longer-lasting collagen changes. On the other hand, carboxytherapy increased elastic fibers while radiofrequency did not.15PubMed. Comparison of the effects of carboxytherapy and radiofrequency on skin rejuvenation This suggests the two treatments may complement each other rather than compete, each affecting a different structural component of the skin.
Hair Loss
A less well-known application of carboxytherapy is for certain types of hair loss, particularly alopecia areata, the autoimmune condition that causes patchy bald spots. The rationale ties back to the improved blood flow mechanism: hair follicles need a steady nutrient supply, and boosting microcirculation to the scalp could help support follicle function.
In one clinical study, patients with alopecia areata treated with carboxytherapy alone showed about 50% hair regrowth. When carboxytherapy was combined with intralesional corticosteroid injections (a standard treatment for the condition), regrowth jumped to roughly 79%, compared to about 70% for corticosteroids alone.16PubMed. Comparative study for treatment of alopecia areata using carboxy therapy, intralesional corticosteroids, and a combination of both Dermoscopic analysis of treated scalps has shown reductions in markers of damaged hair like broken shafts and dark dots, alongside the emergence of new regrowing hairs.17PubMed. Study of the efficacy of carboxytherapy in alopecia
These results are encouraging but still come from small trials. Carboxytherapy for hair loss is not yet a mainstream treatment, and anyone considering it should understand that most dermatologists would position it as an adjunct to established therapies rather than a standalone solution.
What a Session Actually Feels Like
During a carboxytherapy session, a practitioner uses a device that regulates the flow rate, volume, and speed of CO₂ delivery. A thin needle (typically 30-gauge, about the diameter of an insulin needle) is inserted just under the skin, and the gas flows in at a controlled rate. In clinical trials for under-eye dark circles, for example, typical flow rates range from 30 to 60 milliliters per minute, with sessions repeated weekly for about six weeks.18PubMed. A randomized comparative study of the effect of two different flow rates of carboxytherapy in the treatment of infraorbital dark circles
As the gas enters, you feel a sensation of pressure or distension in the area, and the skin may puff up temporarily with a crackling texture (called crepitus, which is simply gas sitting in the tissue). The whole session usually takes somewhere between 15 and 30 minutes depending on how large the treatment area is. No general anesthesia is involved, and there is essentially no downtime: the gas absorbs fully within minutes to hours, and any swelling or redness at the injection site tends to resolve quickly.
Pain is the elephant in the room. Some patients find the injections uncomfortable, and pain has been identified as the main factor limiting wider adoption of the procedure in practice.19PubMed. Effects of transcutaneous electrical nerve stimulation on pain intensity during application of carboxytherapy in patients with cellulite: A randomized placebo-controlled trial The discomfort varies with the treatment area: areas with less subcutaneous fat (like the face) tend to be more sensitive. Researchers have tested applying transcutaneous electrical nerve stimulation (TENS) during the procedure and found it effective at reducing pain, which gives practitioners a practical option for patients who struggle with the sensation.
Side Effects and Safety Profile
A systematic review of carboxytherapy across multiple dermatological uses found that side effects during and after treatment were consistently mild and temporary. The most commonly reported were redness at the injection site, minor pain, crepitus (the crackling sensation from gas under the skin), and small bruises.20PubMed. Carboxytherapy in dermatology: A systematic review All of these resolved on their own, typically within an hour or so.
Serious complications are rare but not impossible. If too much gas is injected into one area, or the injection goes deeper than intended, there is a risk of prolonged subcutaneous emphysema (gas trapped in tissues for an extended period). Inadvertent fat loss at injection sites intended only for skin rejuvenation has also been reported, which happens when the CO₂ disrupts fat cells in an area where fat reduction was not the goal. These risks underscore the importance of having the procedure performed by someone trained in proper injection depth, volume, and flow-rate settings.
There are no broadly agreed-upon absolute contraindications published in the literature, but common-sense exclusions apply. People with severe cardiopulmonary disease, active infections at the treatment site, or blood-clotting disorders are typically advised against the procedure. Pregnancy is generally considered a contraindication as well, mostly out of caution rather than documented harm.
Topical Carboxytherapy
Not everyone wants needles near their face, which has driven interest in a needle-free alternative: topical carboxytherapy gels. These products work by generating CO₂ through a chemical reaction on the skin’s surface, allowing the gas to permeate through the outer skin layers without injection. A topical gel formulation has been shown to increase microcirculation and capillary growth in a manner similar to what injected CO₂ achieves.2PubMed Central. Topical Carboxytherapy for Skin Rejuvenation
Topical formulations have also been explored for wound healing in settings where injection might not be appropriate. A preliminary investigation into a transcutaneous carboxytherapy gel for small diabetic foot ulcers found that all ten subjects showed clinical improvement after four weeks of use, suggesting potential as a non-invasive adjunct for routine home wound care.21Journal of Clinical Research and Case Studies. Use of a Transcutaneous Carboxytherapy Gel for Treating Small Diabetic Foot Ulcers: Preliminary Investigations That study was very small and uncontrolled, so the results are preliminary, but it highlights an interesting direction for the technology beyond the cosmetic clinic.
The trade-off with topical delivery is predictable: you avoid the discomfort and risks of injection, but the CO₂ does not penetrate as deeply or as precisely. For superficial skin-quality improvements, a topical gel may be sufficient. For deeper targets like fat deposits, cellulite bands, or hair follicles, the injectable version is likely necessary to deliver enough gas to the right tissue layer.
How Many Sessions and How Long Do Results Last
Most clinical protocols call for somewhere between six and ten sessions, usually spaced one week apart. Skin-quality improvements like increased collagen and elastic fiber density tend to build gradually over the course of treatment rather than appearing after a single session. Some studies evaluated outcomes six weeks after the final treatment and still observed the benefits, but long-term data beyond a few months is sparse for most applications.
Cellulite and fat reduction results face the same durability question that plagues all non-surgical body-contouring treatments: the treated fat cells may be damaged, but if you gain weight afterward, remaining fat cells in the area can enlarge again. Maintenance sessions are commonly recommended by practitioners, though the ideal frequency for maintenance has not been well established in the literature. For dark circles and stretch marks, the structural improvements to collagen and blood-vessel networks may persist longer, but periodic touch-ups are generally expected.
Where Carboxytherapy Sits Among Other Treatments
Carboxytherapy occupies an interesting middle ground in the aesthetic landscape. It is more invasive than purely topical treatments or LED therapy, but far less invasive than surgery or even aggressive laser resurfacing. For cellulite, it performs comparably to mesolipolysis. For stretch marks, it holds its own against platelet-rich plasma. For skin rejuvenation, it trades off with radiofrequency in interesting ways, offering elastic-fiber benefits that radiofrequency misses while lacking the longer-lasting collagen remodeling that radiofrequency provides.
Its biggest limitation is the thinness of the evidence base. Most published trials are small, many lack control groups, and long-term follow-up is uncommon. A systematic review across dermatological uses confirmed the procedure’s safety and noted positive outcomes across multiple conditions, but also highlighted the need for larger randomized controlled trials to firm up the evidence.20PubMed. Carboxytherapy in dermatology: A systematic review In most countries, carboxytherapy devices are cleared as medical devices, but the procedure itself is not specifically approved by bodies like the FDA for individual cosmetic indications in the way a drug might be. That does not mean it is unsafe or unregulated, but it does mean the practitioner’s skill and judgment play an outsized role in your outcome. Choosing someone with specific training in carboxytherapy protocols, not just general aesthetic experience, makes a meaningful difference.