How Carboxytherapy Works: Mechanism and Evidence

A clinician may have suggested carboxytherapy for under-eye darkness, small scars or uneven skin texture, and you want to know what carbon dioxide actually does. In injectable carboxytherapy, medical-grade CO₂ is delivered through a fine needle into selected tissue layers. The gas temporarily expands the tissue; changes in local blood flow and oxygen exchange are proposed to stimulate a tissue response. But “better microcirculation” does not automatically mean dark circles, wrinkles or a bulge of fat will disappear. Evidence differs for each concern.

Clarify the term before discussing results. Some salons also call a needle-free mask or gel “carboxytherapy” because it is intended to release CO₂ at the skin surface. Its ingredients, penetration and established effects are different from those of gas injections; injection-study findings cannot be transferred to a mask. It is also not fractional CO₂ laser treatment: in a laser, carbon dioxide identifies the laser medium, not a gas injected beneath the skin.

What happens after gas is injected, and what has actually been demonstrated?

A clinician introduces a selected volume of medical-grade gas with a dedicated system. It spreads through nearby tissue and is gradually absorbed; carbon dioxide is a normal substance in metabolism and is eliminated chiefly through the lungs. That explains why the gas should not remain under the skin indefinitely, not why an injection should be assumed harmless. Needle punctures, tissue expansion, depth of delivery and underlying health all matter.

There are three distinct levels of explanation that advertisements often blur. First, the immediate mechanical effect: tissue expansion and a transient feeling of pressure. Second, a proposed physiological effect: a changed local environment may influence vascular responses and how haemoglobin releases oxygen (the Bohr effect). Third, the clinical outcome: perhaps a dark patch is less visible, a scar looks different or skin feels firmer. The first two do not establish the third. Clinical benefit must be measured in studies involving people with the same concern as yours.

Reviews discuss possible influences on microcirculation, new small-vessel formation and connective-tissue remodelling. These remain proposed mechanisms whose importance may vary with site and protocol. No device can simply be promised to “oxygenate every cell”, “remove toxins” or dissolve a local fat deposit. Nor is redness evidence of a durable future benefit: a visible reaction today and an outcome weeks later are different endpoints.

For which problem might the mechanism be relevant?

Start with the reason for what you see, not the procedure name. Under-eye darkness, for example, may reflect pigment, visible vessels, thin skin, anatomical shadows or a combination. Even if an effect on blood vessels helps one person, it will not fill a pronounced tear trough or reliably erase inherited pigmentation.

What you want to change	Why carboxytherapy is discussed	Main limitation
Dark under-eye area	Small clinical investigations have examined injected CO₂ for periorbital hyperpigmentation.	Vascular, pigmentary and shadow-related components need separating; reliable long-term effects are insufficiently established.
Fine wrinkles and skin quality	Courses have been studied for changes in skin characteristics and apparent firmness.	Small studies do not amount to a guaranteed lift or a replacement for treatments with better-supported indications.
Stretch marks and atrophic scars	Connective-tissue change is a proposed mechanism.	Scar age and depth matter; complete erasure is not a realistic expectation.
Cellulite and local fat deposits	Some studies have examined contour or volume changes.	It is not a weight-loss method; data quality and comparability are limited, and unwanted effects on fat are possible.

Agree on a specific observable outcome with the clinician: for instance, less of one under-eye colour component or a smoother small scar. “Rejuvenation” alone is too vague to judge later. If your main aim is a visible jawline lift, a deep fold correction or filling an anatomical hollow, the basic mechanism of carboxytherapy is unlikely to address it directly.

How persuasive is the research when testimonials are positive?

A 2025 systematic review covered 41 publications on carboxytherapy in dermatology and aesthetic medicine and described promising findings. Yet it combined very different concerns, from facial problems to scars and fat deposits. A positive overall review cannot predict the size of an individual benefit; different protocols and outcome measures complicate comparisons. An earlier systematic review also noted encouraging studies, but “investigated” does not mean “standardised for every indication”.

For dark circles there are small clinical trials, including comparisons against fractional laser on different sides of the face and investigations without a control group. Without a comparator, change could reflect time, skincare, photography lighting or participant expectations rather than the injected gas alone. A 2026 imaging study reported discomfort and withdrawals; it lacked a control group, so the observed changes cannot confidently be attributed to the injections. In the 2026 periorbital imaging study, 25 of 78 participants discontinued the seven-week course because of discomfort, leaving 53 completers. This matters when judging tolerability; without a control group, the study cannot establish whether injections caused the observed benefit.

Instead of only looking at attractive before-and-after photographs, ask which study supports your particular area, which method it tested and how long results were followed. “Evidence is preliminary; any improvement may be modest” is a reasonable clinical answer, not a sign of incompetence.

What is a session like and what might you feel?

First the clinician examines the skin and cause of the concern, reviews medical conditions and medication, and discusses realistic outcomes. For injectable treatment, the skin is cleansed, a suitable device delivers medical gas and injections are made at chosen points. Depth, volume and locations vary with the aim. There is no single correct pattern for every body area; a qualified professional must choose technical settings, not a social-media video.

You might feel a needle prick, pressure, distension, tingling or brief burning. Some people notice the gas moving beneath the skin. Around the eyes even moderate swelling can feel more conspicuous than elsewhere. Ask which sensations are expected, how discomfort is managed and what symptoms would make the clinician stop. You need not tolerate sharp, unusual or worsening pain in pursuit of a supposed benefit.

Promises of “completely painless” treatment or “no one will notice when you leave” are unreliable. Puncture marks, sensitivity, puffiness and bruises can occur. Their visibility depends on the site, injection technique, individual tendency to bruise and medicines. Feeling well is not the same as looking unchanged on camera: you may be fit for computer work while skin changes remain visible in a close-up.

How should you plan recovery before a meeting or photo session?

When	What you might notice	Practical response
Immediately after injections	Pinpoint marks, redness, local pressure or swelling.	Get individual aftercare instructions, including when makeup, exercise and heat are allowed.
Over the next few days	Tenderness may persist or a bruise appear; the face can look different than it did on leaving.	Do not judge efficacy by early swelling or schedule essential close-up photos without a time buffer.
Once reactions settle	It becomes easier to separate temporary swelling from a hoped-for benefit.	Compare pictures under matching light and facial position; review the result before agreeing to another session.

No fixed number of days guarantees that treatment will be invisible for everyone. With a wedding, trip or presentation ahead, avoid trying your first injections immediately before the event. Ask about review timing, bruising and what to do if swelling is greater than expected. Rules for makeup, sauna, pools and workouts depend on the punctures and skin response; personalised instructions matter more than generic online advice.

When should you postpone treatment or choose another approach?

Injectable carboxytherapy is not routine home skincare. Active inflammation or infection at the site calls for treatment first. Tell the clinician about pregnancy or breastfeeding: safety evidence for elective cosmetic use is inadequate, so postponing is generally the more prudent choice. Significant heart or lung disease, clotting problems, anticoagulant treatment or a history of serious reactions require individual medical assessment. Never stop prescribed medication on your own.

Mention recent surgery, implants or fillers in the intended area, unexplained skin changes and flare-ups of chronic disease. Not all of these automatically prohibit treatment, but their effect on risk must be discussed. A suspicious pigmented lesion, inflammatory skin condition or another undiagnosed cause needs assessment rather than cosmetic gas injections.

Warning signs include escalating severe pain, rapidly expanding swelling, spreading hot redness, discharge, high fever, vision changes or significant breathing difficulty. Do not wait for the next routine appointment: seek prompt medical assessment, and vision or breathing symptoms require emergency care. Serious complications are not inevitable; the point is to recognise a problem early.

How does carboxytherapy differ from nearby techniques?

Needle-free masks involve applying ingredients to skin, without gas injections, although contact irritation or ingredient sensitivity is possible. Fractional CO₂ laser is a different procedure that uses controlled thermal injury, with different restrictions and recovery. Fillers add volume; botulinum toxin reduces activity in selected muscles. These mechanisms are not interchangeable.

For dryness or tightness, start by reviewing barrier-friendly skincare. If vessels or pigmentation drive the complaint, seek a diagnosis and a more targeted option. For scars, identify type, age and depth: laser, microneedling or observation may be discussed for different reasons. Compare treatments by how plausibly they solve your own problem at an acceptable level of risk, not by fashionable labels.

What should you ask before consenting to injections?

What is causing my skin change? Ask the clinician to show what they found on examination and how CO₂ is supposed to affect it.
Are you offering injections or a topical product? Clarify what gas or product is used, its source, sterility, device and practitioner qualifications.
What evidence supports the proposed outcome? Request research for your specific treatment area, not simply the slogan “improved microcirculation”.
How will we decide not to continue? Discuss the expected size of any change, the possibility of no benefit and the full-plan cost without presuming a mandatory course.
What changes my personal risk and recovery? Disclose illnesses, medication, allergies and upcoming commitments; ask for written aftercare and a contact for complications.

If someone promises the same outcome to everyone, cannot identify the technique or risks, or pushes immediate injections, taking time to decide is sensible. The purpose is not to prove that carboxytherapy “works in general”, but to decide whether you have sufficient reason to choose it over a better-studied or gentler method—or no intervention.

Frequently asked questions

Can I do carboxytherapy myself at home?

Gas injections require medical assessment, sterile technique and appropriate equipment; injecting gas at home is unsafe. A topical mask is another product category and its ingredients and directions must be checked separately.

Will CO₂ remain under the skin?

Injected gas is ordinarily absorbed and eliminated gradually. However, persistent or worsening pressure, pain or unusual swelling needs assessment; do not attempt to “move the gas out” yourself by massaging the area. Prolonged gas accumulation in tissue (subcutaneous emphysema) has also been reported; unusual or persistent swelling needs clinical assessment.

Is there a test that guarantees my result in advance?

No reliable universal test exists. Examination, identifying the cause and discussing evidence quality support a better-informed choice but cannot predict an individual's response with certainty.