What is inside
Lemon Bottle is a branded liquid from SID Medicos, a company in Seoul, South Korea. It is promoted online and on social media as a “lipolysis” or “fat dissolving” solution for stubborn fat, and regulators in Switzerland, the United States and the UK have all described it being injected, although its distributor has told regulators it is a cosmetic for external use only. The maker lists three main ingredients, riboflavin (vitamin B2), bromelain (enzymes from pineapple) and lecithin (a fatty substance from soybeans or egg yolk), plus unnamed “natural ingredients”. The full formula and amounts are not published.
What is actually in a given pack is uncertain. When the Swiss regulator tested samples from different sources in 2024, it could not find the listed ingredients; one contained only caffeine.
Declared composition, from packaging and marketing as summarised by Swissmedic: mainly bromelain, lecithin and riboflavin, plus several unspecified natural ingredients. No quantitative formula has been published, and the product has no PubChem, CAS or pharmacopoeial identity. Marketing quoted in FDA’s 2025 warning letters attributes the effect to lecithin breaking down fat-cell membranes and to riboflavin helping the body discharge dissolved fat faster than normal metabolism; those are the seller’s claims, not findings.
Analytical data: the official Swissmedic laboratory analysed samples of “Lemon Bottle” lipolysis solution obtained from various sources and reported in March 2024 that the ingredients did not match the declaration and varied greatly from pack to pack. In one sample the only substance found was caffeine; in another none of the listed ingredients could be detected. Swissmedic described these samples as falsifications. No independent peer-reviewed analysis, sterility or endotoxin testing, or stability data for authentic product were found, and nothing is known about the pharmacokinetics of any component after subcutaneous injection of this product.
Ingredient: Riboflavin
Riboflavin is vitamin B2, an essential nutrient found in milk, eggs, meat and fortified cereals. The body turns it into two helper molecules that many enzymes need to release energy from food, including the enzymes that burn fatty acids for fuel inside cells. It is bright yellow and breaks down in light.
That role in normal metabolism is the basis of the marketing claim, but it does not follow that injecting riboflavin into a patch of fat breaks that fat down or clears it faster. No study showing either effect was found. Riboflavin, in its phosphate form, is a legitimate ingredient of FDA-approved intravenous multivitamins and of eye drops used in a corneal procedure; neither has anything to do with fat reduction.
Riboflavin (7,8-dimethyl-10-D-ribityl-isoalloxazine, C17H20N4O6, 376.4 g/mol, PubChem CID 493570) is converted by riboflavin kinase and FAD synthetase to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These are prosthetic groups of flavoproteins including respiratory-chain complexes I and II and the acyl-CoA dehydrogenases that catalyse the first step of mitochondrial fatty-acid β-oxidation. That is the intracellular oxidation of fatty acids already released from triglyceride; riboflavin is not a lipase, a detergent or an adipocytolytic agent. No evidence was found that extra riboflavin in a person who is not deficient increases fat oxidation, and PubMed contains no study of locally injected riboflavin reducing subcutaneous fat.
Riboflavin is water-soluble and photolabile. Its 5’-phosphate ester is the photosensitiser in Photrexa and Photrexa Viscous, FDA-approved in 2016 for corneal collagen cross-linking with ultraviolet light in progressive keratoconus, and is the riboflavin source in intravenous multivitamin products such as Infuvite Adult.
Ingredient: Bromelain
Bromelain is a mix of protein-digesting enzymes taken from the stem and fruit of the pineapple plant. It is sold as a dietary supplement and is used in food processing to tenderise meat. The FDA has approved one medicine built on pineapple-stem enzymes, NexoBrid, a gel spread on severe burns for a few hours to dissolve dead, charred tissue; it is not injected.
In lab dishes, a 2012 study reported that stem bromelain stopped immature mouse fat cells from maturing and caused mature ones to die and release their fat. That is a cell-culture result. No study was found showing that injecting bromelain into human fat reduces it, and the effects of injecting a protein-digesting enzyme under human skin have not been studied.
Bromelain is a crude extract of Ananas comosus containing several cysteine proteases, principally stem bromelain (EC 3.4.22.32) and fruit bromelain (EC 3.4.22.33), with smaller amounts of ananain and comosain; it is a protein mixture, not a single molecule. The enzymatic debriding agent anacaulase-bcdb (NexoBrid), a mixture of pineapple-stem enzymes, was approved by the FDA on 2022-12-28 as a topical gel applied for four hours to remove eschar in adults with deep partial-thickness or full-thickness thermal burns, based on two trials in 357 patients.
Adipocyte data: Dave et al. (PLoS One 2012) reported that stem bromelain irreversibly inhibited differentiation of 3T3-L1 preadipocytes by down-regulating C/EBPα and PPARγ, and in mature 3T3-L1 adipocytes induced apoptosis and lipolysis through Akt inhibition and augmented TNF-α signalling, with reduced perilipin and PDE3B expression. These are in-vitro findings in a mouse cell line at culture concentrations. No animal or human study of injected bromelain for localised fat reduction was found.
Ingredient: Lecithin
Lecithin is a general name for a family of fatty substances called phospholipids, the main building blocks of cell membranes. Commercial lecithin comes mostly from soybeans, sunflower seeds and egg yolk and is widely added to foods to keep oil and water mixed. Its main component is phosphatidylcholine.
Phosphatidylcholine has a long history in injectable “fat dissolving” treatments, usually mixed with a bile salt called deoxycholate; the FDA names both as common ingredients of unapproved fat-dissolving injections. A 2004 laboratory study found that in such mixtures the fat-destroying effect came mainly from the deoxycholate, which acts like a detergent, rather than from the phosphatidylcholine. No study was found showing that lecithin without a detergent reduces fat when injected.
Lecithin is a mixture of glycerophospholipids, chiefly phosphatidylcholine (PC) with phosphatidylethanolamine, phosphatidylinositol and phosphatidic acid, whose proportions depend on source and fractionation; it has no single formula. PC is amphiphilic and does not dissolve in water as single molecules, so aqueous injectables require a solubiliser or form liposomes.
Rotunda et al. (Dermatol Surg 2004) compared a clinical PC injection, isolated sodium deoxycholate and the laboratory detergents Triton X-100 and Empigen BB in cell culture and porcine tissue. The PC formula and deoxycholate alone produced comparable loss of cell viability, membrane lysis and disruption of fat and muscle architecture, similar to the laboratory detergents. The authors concluded that the formula works primarily as a detergent causing nonspecific cell lysis and that deoxycholate is the major active component. Deoxycholic acid was later approved on its own as Kybella. The three declared main ingredients of Lemon Bottle do not include deoxycholate or another recognised detergent, so the mechanism established for PC–deoxycholate products does not carry over; the lecithin content and how it is solubilised are unpublished.
Why researchers might study these together
The maker’s explanation is a chain of steps. Marketing quoted in FDA warning letters says lecithin breaks down fat-cell membranes and riboflavin helps the body discharge the dissolved fat faster than normal metabolism; bromelain, a protein-digesting enzyme, is the third listed ingredient. Each step borrows a real property of the ingredient, but the leap from that property to dissolving fat under the skin has not been tested.
No clinical trial of Lemon Bottle is registered on ClinicalTrials.gov, and no peer-reviewed study of the product was found in PubMed. The laboratory data relevant to its ingredients are one cell-culture study of bromelain and older work on phosphatidylcholine mixtures, where the fat-destroying effect came from a detergent that Lemon Bottle does not list. The combination has never been tested in animals or people.
Framed as a hypothesis, the proposed mechanism has three parts: disruption of adipocyte membranes by phospholipid (lecithin), pro-apoptotic and lipolytic effects on adipocytes (bromelain, by analogy with the 3T3-L1 data of Dave et al., 2012), and faster oxidation of released fatty acids (riboflavin, by analogy with FAD’s role as cofactor of the acyl-CoA dehydrogenases). None of the three analogies has been tested in vivo for this purpose, and there is no published rationale for their combination or proportions.
The membrane-disruption step is the weakest link: in the PC–deoxycholate literature, cytolytic activity was attributed to the detergent rather than to PC (Rotunda et al., 2004), and no detergent is declared. The riboflavin step assumes that cofactor supply limits fat oxidation, for which no evidence in non-deficient tissue was found. The bromelain step extrapolates from a mouse cell line to human subcutaneous tissue. Finally, Swissmedic’s laboratory findings mean that even a well-designed study would first need to establish what the product actually contains. No trial is registered and no animal study of the product was found.
Regulatory picture
Approval: no medicines regulator has approved Lemon Bottle. Its distributor told the Swiss regulator in 2024 that the genuine product is a cosmetic for external use only. No approval as a drug or medical device by South Korea’s Ministry of Food and Drug Safety, and no statement from it about this product, was found.
Regulators that have acted: Switzerland (2024) classed the injected product as an unauthorised medicine that may not be sold or used, and found falsified samples. The US FDA (2025) sent warning letters to five online sellers calling it an unapproved new drug, because a product sold to dissolve fat is legally a drug. The UK pharmacy regulator (2025) warned pharmacists about supplying or injecting it. No statement specific to Lemon Bottle from the UK MHRA or Australia’s TGA was found.
United States: FDA held that claims such as “LEMONBOTTLE LIPOLYSIS” and “non-surgical alternative to liposuction” establish intended use to affect the structure or function of the body, making the product a drug under section 201(g)(1) and, with no approved application, an unapproved new drug under sections 505(a) and 301(d). By contrast, deoxycholic acid injection (Kybella, NDA 206333, approved 2015-04-29) is labelled only for moderate to severe submental fullness in adults. Its approval rested on two randomised, double-blind, placebo-controlled trials (1,022 subjects) with at least 2-grade composite responses of 13.4% versus under 0.1% and 18.6% versus 3.0% on placebo, and its label warns of marginal mandibular nerve injury, dysphagia and injection-site ulceration and necrosis. FDA’s consumer page calls Kybella the only FDA-approved fat-dissolving injectable.
Switzerland: the cross-agency Expert Panel for Delimitation Questions classified the injected product as a medicinal product; a June 2024 addendum maintained this despite cosmetic labelling.
Compounding: the 503A framework concerns bulk ingredients, not finished imported products, so status is recorded as unknown.
