Fat-dissolving injections (injection lipolysis)

What fat-dissolving injections are

What all variants have in common is the promise of reducing fat in a targeted way at one spot, without surgery. Technically, four groups can be distinguished. First, deoxycholic acid, a bile acid that occurs naturally in the body and is approved as a medicine for treating fat under the chin. Second, classic injection lipolysis with a blend of phosphatidylcholine and deoxycholate, which has been widespread in aesthetic medicine in Germany since the 2000s.

Third, products such as Lemon Bottle, which are sold as cosmetics and injected as fat dissolvers. Fourth, the so-called lipotropic injections, often called Lipo-B, Lipo-C or MIC: blends of methionine, inositol, choline, vitamin B12 or L-carnitine that are supposed to stimulate fat metabolism. These groups have little to do with each other except the name.

How it works

Deoxycholic acid acts as a detergent: injected into fatty tissue, it destroys fat cells, which is called adipocytolysis. The effect remains local, where it is injected. For the phosphatidylcholine blends, it was long unclear what role the phosphatidylcholine plays. In a randomized trial, however, it made no difference whether it was in the blend or not. A newer phase 2 trial with pure soy phosphatidylcholine, by contrast, found an effect on its own as well, so the question is not conclusively settled.

For lipotropic injections there is a plausible background, but no established mechanism: choline, methionine and inositol play a role in the liver’s fat metabolism, L-carnitine in the transport of fatty acids into the mitochondria. That the injection breaks down body fat as a result has not been shown in humans. Deoxycholic acid and the lipolysis blends target localized fat deposits, not body weight.

What the studies show

REFINE-1 and REFINE-2: the approval trials

Jones 2016 (Dermatol Surg) randomized 506 adults who were dissatisfied with moderate or severe fat under the chin. An improvement of at least one grade, in the judgment of both the physicians and the participants, was achieved by 70.0 versus 18.6 percent; of two grades by 13.4 versus 0 percent. In the physicians’ judgment, 55 percent had improved by one grade after two treatments, and 75 percent after four.

Humphrey 2016 (J Am Acad Dermatol) confirmed this with 516 participants: 66.5 versus 22.2 percent for one grade, 18.6 versus 3.0 percent for two grades. 85.7 percent of adverse events concerned the injection site. Follow-up was limited to 44 weeks.

The meta-analysis and its caveat

Inocêncio 2023 (Clinics) found five suitable randomized trials. Deoxycholic acid was better than placebo on all efficacy outcomes, but more often caused induration, pain, redness, numbness, swelling, itching, nodules, headache and abnormal sensations. Only two trials had a low risk of bias, and all showed possible influence from industry funding.

Rotunda 2009: is phosphatidylcholine needed?

In this randomized, double-blind trial with 42 participants, one group received deoxycholate alone, the other the usual blend with phosphatidylcholine. Both groups showed only slight visible improvement, with no difference in effect or side effects. The authors interpreted this as an indication that phosphatidylcholine contributes nothing to the blend, and as proof of concept for deoxycholate.

Choi 2025: phosphatidylcholine alone

The Korean phase 2 trial (Clin Ther) compared two concentrations of soy phosphatidylcholine with placebo in 96 participants, up to six sessions two weeks apart. Four weeks after the last administration, the double chin improved in the investigators’ judgment in 69.7 percent with the lower and 48.4 percent with the higher concentration, and in 22.6 percent on placebo. Only the difference for the lower concentration was significant.

What users report

An analysis of online reviews on the RealSelf platform (Fijany 2026, Aesthet Surg J) compared 585 reviews of Kybella with 753 of liposuction of the chin, analyzed with language models. 55.2 percent of Kybella reviews were positive, compared with 83.4 percent for liposuction. Kybella reviews more often expressed sadness and anxiety and less often joy. Such analyses are not a controlled trial; they reflect the satisfaction of those writing, not the measured effect.

Where the data stop

• Other parts of the body. Deoxycholic acid is approved and tested in large trials only for fat under the chin. For the abdomen, hips or thighs, trials of this size are missing.
• Lemon Bottle. There is no controlled trial. Swissmedic found none of the declared ingredients in samples.
• Lipotropic injections. We found no controlled trial of Lipo-B, Lipo-C or MIC injections for weight loss. What has been studied for oral intake of individual substances cannot be transferred to the injection.
• Independent data. All large deoxycholic acid trials were funded by the manufacturer.

Status, approval and legal

Deoxycholic acid is prescription-only in Germany (Annex 1 of the German Ordinance on Prescription-Only Medicines). According to a 2019 Dear Healthcare Professional Letter (Rote-Hand-Brief), Kybella was approved at European level but was not marketed in Germany. According to a 2010 review, the blend of phosphatidylcholine and deoxycholate was approved as Lipostabil N only for infusion in fat embolism; injection into fatty tissue is an off-label use.

Swissmedic classifies Lemon Bottle as a non-approved medicine: products for injection fall under therapeutic products law regardless of injection depth and may not be sold as cosmetics. The distributor states that the original is a cosmetic for external use only. L-carnitine for parenteral use is prescription-only in Germany.

Safety

With deoxycholic acid, most side effects are local and temporary: swelling, pain, numbness, induration. In REFINE-1, 4.3 percent of those treated experienced a mostly mild, temporary weakness of the nerve that moves the corner of the mouth. The 2019 Dear Healthcare Professional Letter warns of necrosis at the injection site, up to arterial necrosis; anyone who has had such a reaction must never be treated with it again.

With products without approval, it is not even clear what is in the syringe: in one Lemon Bottle sample Swissmedic found only caffeine, and in others none of the stated substances. Injections into fatty tissue belong in the hands of a physician, with approved products and clean technique.

Sources

• Jones DH et al., Dermatol Surg 2016 – REFINE-1, deoxycholic acid phase 3
• Humphrey S et al., J Am Acad Dermatol 2016 – REFINE-2, deoxycholic acid phase 3
• Inocêncio GSG et al., Clinics 2023 – meta-analysis of deoxycholic acid, efficacy, safety, industry bias
• Rotunda AM et al., Dermatol Surg 2009 – deoxycholate alone versus phosphatidylcholine/deoxycholate, randomized
• Choi SY et al., Clin Ther 2025 – soy phosphatidylcholine (AYP-101), phase 2
• Hoffmann K, Hautarzt 2010 – injection lipolysis, off-label use of Lipostabil N
• Fijany AJ et al., Aesthet Surg J 2026 – analysis of online reviews: Kybella versus liposuction
• AkdÄ – Dear Healthcare Professional Letter (Rote-Hand-Brief) Kybella (deoxycholic acid), January 16, 2019: necrosis at the injection site
• Swissmedic – warning about the illegal medicine “Lemon Bottle” lipolysis solution (March 26, 2024)
• German Ordinance on Prescription-Only Medicines (Arzneimittelverschreibungsverordnung), Annex 1