What is the difference between fat-dissolving injections, DCA, and PPC?
Author: In-Yong Kim, MD | Lieul Dermatology Clinic | Dermatology, aesthetic and body contouring procedures
Written and medically reviewed by: In-Yong Kim, MD
Published: August 31, 2026 | Last updated: August 31, 2026
This article provides general medical information on injectable treatments intended to reduce submental fat (commonly called a double chin) and localized fat, including deoxycholic acid (DCA), phosphatidylcholine (PPC), and compounded formulations. It is based on original research articles and reports from public healthcare institutions in Korea and abroad. It is not intended to replace individualized diagnosis or treatment, and outcomes may vary from person to person.
What Is the Difference Between Fat-Dissolving Injections, DCA, and PPC?
The main differences are their ingredients and the strength of the supporting clinical evidence.
DCA is a bile acid that disrupts cell membranes and is supported by large Phase III clinical trials as well as approved indications in Korea. PPC is a phospholipid with some mechanistic evidence, but large-scale clinical data remain limited. What is commonly referred to as a fat-dissolving or cocktail injection generally refers to an off-label formulation containing a mixture of several ingredients.
Category | DCA (Deoxycholic Acid) | PPC (Phosphatidylcholine) | Mixed Formulations |
|---|---|---|---|
Type of ingredient | Bile acid / surfactant | Soy-derived phospholipid | Mixtures such as DCA, GPC, HPL, carnitine¹ |
Primary mechanism | Direct cell membrane disruption (adipocytolysis)² | Relative selectivity for mature adipocytes in cellular and animal studies³ | Varies by formulation; no standardized composition¹ |
Human histologic evidence | Available (days 1, 3, 7, 28)⁴ | Limited | None |
Phase III trials | Available (n=1,022)⁵ | No large-scale trials⁶ | None¹ |
Approved indication in Korea | Submental fat (approved products available) | No approved indication for this purpose | None; off-label use |
Overall evidence | Relatively strong, for one anatomical area | Low | Difficult to assess¹ |
How Does DCA Reduce Fat?
DCA does not metabolically burn fat. It physically disrupts adipocyte cell membranes through a detergent-like action.
Once adipocytes are destroyed, cellular debris is cleared by macrophages and processed through the body's normal clearance mechanisms.
DCA is a naturally occurring bile acid in the human body and has the ability to emulsify lipids. Initially, PPC was believed to be the active ingredient in these injectable formulations, while DCA was regarded primarily as a solvent used to keep PPC in solution. However, a cell membrane lysis study published by Rotunda et al. in Dermatologic Surgery in 2004 suggested that sodium deoxycholate, rather than PPC, was the major active component responsible for cellular destruction. The study concluded that sodium deoxycholate acted as a nonspecific detergent capable of disrupting cell membranes.²
In other words, the ingredient once regarded mainly as a solvent turned out to play the major role.
If DCA Acts Like a Detergent, Why Doesn't It Damage Skin and Muscle in the Same Way?
One important reason is the presence of proteins.
Protein-rich tissues containing substances such as albumin can bind DCA and reduce its cytolytic activity. Adipose tissue has less of this buffering capacity, allowing DCA to exert a relatively stronger effect.
In a 2010 study by Thuangtong et al. examining tissue selectivity, DCA lysed all tested cell types under in-vitro conditions. When injected into adipose tissue, however, adipocytes underwent cell death while other cell types were relatively less affected. The cytolytic activity of DCA was also reduced in the presence of physiological concentrations of albumin or in protein-rich tissues.⁷ The study also observed redistribution of injected DCA within several hours.⁷
The clinically important point is that this represents relative selectivity, not absolute selectivity. If DCA is injected too superficially near the dermis, or if excessive amounts are administered to areas with a very thin fat layer, damage to surrounding tissue may still occur.
What Happens During the Four Weeks After a DCA Injection?
Day 1: adipocyte destruction. Day 3: neutrophil-dominant inflammation. Day 7: macrophage clearance. Day 28: resolution of inflammation and thickening of fibrous septa.
In a Phase I open-label study, different doses were injected into human abdominal fat, and the tissue was subsequently excised during abdominoplasty for histological analysis.⁴
Time | Histological Findings |
|---|---|
Day 1 | Adipocytolysis |
Days 1–3 | Acute localized inflammation dominated by neutrophils |
Day 7 | Decrease in neutrophils; macrophage clearance of cellular debris and free lipids |
Day 28 | Most inflammation resolved; neovascularization, thickening of fibrous septa (new collagen formation), adipose lobule atrophy |
The collagen remodeling observed at day 28 has clinical relevance. When fat volume decreases without corresponding changes in the overlying tissue, skin laxity may become more noticeable; the fibrosis and remodeling occurring during this process may contribute to the resulting contour. In addition, because the number of adipocytes themselves is reduced, the mechanism is consistent with the observed durability of the treatment effect.
How Effective Is DCA According to Clinical Trials?
In the Phase III REFINE-2 trial, 66.5% of patients receiving DCA achieved at least a one-grade composite improvement 12 weeks after their final treatment, compared with 22.2% in the placebo group.⁵
Outcome | DCA | Placebo | Source |
|---|---|---|---|
≥1-grade composite improvement at 12 weeks | 66.5% | 22.2% | REFINE-2, JAAD, 2016⁵ |
≥2-grade composite improvement at 12 weeks | 18.6% | 3.0% | REFINE-2, JAAD, 2016⁵ |
Follow-up of treatment effect | Up to 3 years | — | Aesthetic Surgery Journal, 2021⁸ |
REFINE-1 and REFINE-2 were randomized, multicenter, double-blind, placebo-controlled trials involving 1,022 adults with moderate to severe submental fat.⁵ ⁸
There is, however, an important limitation when interpreting these numbers: these data relate specifically to the submental area. They should not be extrapolated to the abdomen, thighs, or arms, and the approved indication in Korea is likewise limited to submental fat.
What Is the Evidence for PPC Injections?
Mechanistic studies exist, but large-scale human trials establishing efficacy and safety remain limited.
PPC is a soy-derived phospholipid that has historically been used in intravenous preparations for conditions such as fat embolism and dyslipidemia. PPC-DCA formulations have been used for localized fat reduction in parts of South America and Europe, but high-quality clinical trials have been limited, and substantial pharmaceutical development for this indication has not occurred in the United States.⁶
Differences have been reported at the cellular level. In 3T3-L1 cells and animal models, DCA induced cell death in both preadipocytes and mature adipocytes, whereas PPC demonstrated relatively greater selectivity toward mature adipocytes. Strong inflammatory responses were primarily observed following DCA injection.³ These findings suggest a theoretical basis for PPC, but cellular and animal findings cannot substitute for evidence of clinical efficacy in humans.
Are Compounded Fat-Dissolving Injections Safe?
A Korean public healthcare assessment concluded that their efficacy and safety are currently difficult to evaluate adequately.
The National Evidence-based Healthcare Collaborating Agency (NECA) stated in its 2024 Health Technology Reassessment Report on fat-dissolving injections that the efficacy and safety of the various off-label compounded injections currently in clinical use are difficult to assess. The report also highlighted the need for clearer standards regarding injection technique and for larger, longer-term studies.¹
Depending on the clinic, these injections may contain combinations of DCA, choline alfoscerate (GPC), hypotonic pharmacologic lipodissolution agents (HPL), corticosteroids, carnitine, hyaluronidase, and other substances.¹ The lack of standardized formulations means that results obtained with one clinic's formulation cannot be generalized to a different formulation used elsewhere.
What Should You Consider When Choosing a Treatment?
A practical order is: treatment area, then ingredient and approved indication, then clinical assessment by the treating physician.
1. Identify the treatment area first. For submental fat, approved DCA formulations currently have the clearest clinical evidence. For larger areas such as the abdomen or thighs, no injection should be considered a substitute for weight reduction or liposuction.
2. Ask about the exact ingredients, concentrations, and approved indications. Being told only that a treatment is a clinic-specific formulation does not provide enough information.
3. Confirm the number of sessions and treatment intervals. Tissue responses following DCA occur over approximately 28 days, and clinical trial intervals were designed with this process in mind.⁴
4. Understand adverse effects in the context of the mechanism. Because DCA works through cell membrane disruption and a local inflammatory response, swelling, pain, bruising, and numbness are common.⁹
What Are the Possible Side Effects?
Swelling, localized pain, bruising, and numbness are among the most common adverse effects. They generally resolve spontaneously, although serious complications have occasionally been reported.
According to systematic reviews, swelling, localized pain, bruising, and numbness are among the most frequently reported adverse events and generally resolve over time. However, complications requiring more complex management, including skin necrosis, nerve injury, alopecia, and vascular-related events, have also been reported, and standardized treatment protocols for such complications have not yet been fully established.⁹
Frequently Asked Questions
Q. Does fat removed by DCA come back?
A. Adipocytes destroyed by the treatment are cleared by the body.⁴ However, remaining adipocytes can still enlarge with weight gain, meaning the visible contour can change again without appropriate weight management.
Q. How many treatments are needed?
A. The required number varies among individuals, and there is no single number appropriate for everyone. Phase III trials were designed to permit up to six treatment sessions. Because tissue responses continue for approximately four weeks, treatment intervals should take this process into account.⁴ ⁵
Q. When will I begin to see results?
A. Major clinical trial outcomes were assessed 12 weeks after the final treatment.⁵ Immediately after treatment, swelling may temporarily make the area appear larger.
Q. Can I expect the same results in the abdomen or thighs?
A. The strongest evidence currently applies to the submental area. Use in other anatomical areas is generally off-label, and efficacy percentages from submental trials should not be assumed to apply elsewhere.
Q. Which is better, PPC or DCA?
A. Based solely on the level of clinical evidence, DCA is supported by large Phase III trials and human histological data.⁴ ⁵ PPC has demonstrated potentially selective effects in cellular studies,³ but large-scale human clinical evidence remains limited.⁶
Q. What is most important after treatment?
A. Swelling and tenderness may persist for several days and should be monitored. If abnormal sensation, noticeable asymmetry, or changes in skin color occur, patients should promptly contact the medical institution where the procedure was performed.⁹
References and Sources
1. National Evidence-based Healthcare Collaborating Agency (NECA). 2024 Health Technology Reassessment Report: Fat-Dissolving Injections. https://www.neca.re.kr
2. Rotunda AM, Suzuki H, Moy RL, Kolodney MS. Detergent effects of sodium deoxycholate are a major feature of an injectable phosphatidylcholine formulation used for localized fat dissolution. Dermatol Surg. 2004;30(7):1001-1008. https://pubmed.ncbi.nlm.nih.gov/15209790/
3. Selective effect of phosphatidylcholine on the lysis of adipocytes. PMC5413042. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5413042/
4. Walker P, et al. Histological analysis of the effect of ATX-101 (deoxycholic acid injection) on subcutaneous fat: results from a phase 1 open-label study. Dermatol Surg.
5. Jones DH, Carruthers J, Joseph JH, et al. ATX-101 for reduction of submental fat: a phase III randomized controlled trial (REFINE-2). J Am Acad Dermatol. 2016. https://www.jaad.org/article/s0190-9622(16)30129-3/fulltext
6. Safety and Efficacy of Deoxycholic Acid Injection for Reduction of Upper Inner Thigh Fat. ClinicalTrials.gov NCT04054011.
7. Thuangtong R, et al. Tissue-selective effects of injected deoxycholate. Dermatol Surg. 2010;36:899-908. https://onlinelibrary.wiley.com/doi/10.1111/j.1524-4725.2010.01566.x
8. Improvements in submental contour up to 3 years after ATX-101: efficacy and safety follow-up of the phase 3 REFINE trials. Aesthetic Surgery Journal. 2021;41(11):NP1532. https://academic.oup.com/asj/article/41/11/NP1532/6146596
9. Deoxycholic acid in the submental fat reduction: a review of properties, adverse effects, and complications. PMID 32654409. https://pubmed.ncbi.nlm.nih.gov/32654409/
This content is provided for general medical information purposes and does not guarantee the outcome of any specific treatment. Treatment decisions should be made following an in-person consultation and evaluation by a qualified medical professional.
Lieul Dermatology Clinic