Two rashers of raw bacon, a box of syringes and a vial of yellow liquid have been neatly arranged on a kitchen table. “Let’s dissolve some bacon fat together,” says a woman wearing rubber gloves. She lifts a syringe and injects one of the rashers with the yellow solution. Within minutes, the fat starts to disintegrate.

This isn’t a school science experiment. Instead, it’s one of hundreds of videos promoting Lemon Bottle: a new fat-dissolving injection promising miracle results.

In the last six months, Lemon Bottle has become a viral marketing sensation. On TikTok alone, videos tagged #Lemonbottle have been watched 81.5m times. Adverts for treatments costing from £50 an area are common on Facebook Marketplace, Instagram and in high street salon windows.

Google data shows that while UK searches for Lemon Bottle were virtually non-existent until this year, they have since surged – overtaking those for “liposuction” in September and far surpassing interest in other fat-dissolving jabs.

But while the hype has won Lemon Bottle legions of fans, its rapid rollout has divided the aesthetic medicine sector. Some of the country’s leading experts are worried about the product’s long-term safety and effectiveness, a lack of published research, and the way it is being marketed as a risk-free quick fix.

“It really does worry me,” said Dr Sophie Shotter, an aesthetic doctor and trustee of the British College of Aesthetic Medicine. “This is a product that is claiming to be the ‘fastest and strongest’ fat dissolver in the industry, but it doesn’t appear to have clinical evidence.”

Reports of safety issues linked to Lemon Bottle have also risen in recent months. Save Face, a register of accredited practitioners, said it had recorded 90 complaints about the product so far in 2023 – 50 in the past three months – compared with just one complaint in the whole of 2022.

These include claims that customers were left with uneven results, saw no results at all, or suffered prolonged bruising or swelling, infections, abscesses, and, in one case, necrosis, the death of body tissue.

Ashton Collins, Save Face’s director, said it was unclear whether the problems were due to technique, counterfeits or issues with the official Lemon Bottle product itself. But she said in each case the customer had paid for a treatment they believed was Lemon Bottle. “People are seeing it as a magic wand treatment, and they do not appreciate the risks involved,” she said.

Made by Sid Medicos, a company based in Seoul, South Korea, Lemon Bottle is pitched as stronger, safer and more effective than other fat-dissolving injections. While rival products can contain substances such as deoxycholic acid, which are safety tested and proven to dissolve fat cells, Lemon Bottle does not, and instead says it has “all-natural ingredients”.

A full ingredient list does not appear to be available online, and requests for more detail went unanswered last week. But the company website says the “key ingredients” are bromelain, riboflavin and lecithin, which are injected into an area of “stubborn fat” on the face or body.

Sid Medicos says the ingredients then work together to break down fat cells into fatty acid, which is flushed out naturally when you urinate.

At his clinic in Chelsea, west London, Dr Vahe Karimyan, a surgeon, said he regularly saw clients requesting Lemon Bottle. So far, he had treated about 200 patients with it and said they were delighted with the results.

He described the treatment as “virtually painless” and “very good” for “double chins, the abdominal area, love handles, inner thighs and underarms”. He said: “This is a Korean product, and there is [some research] showing it is quite effective. My patients are far more than happy after the procedure. It is very well tolerated in contrast to other products.”

Others are yet to adopt it. Dr Yannis Alexandrides from the 111 Harley Street clinic said the evidence was “too flimsy” for him to feel confident offering Lemon Bottle. “My personal assessment and initial research finds no scientific papers to support the efficacy and safety of this product,” he said.

Amy Morgan, a lecturer in human biology at Liverpool Hope University, agreed there appeared to be a lack of peer-reviewed research. “For example, while there is evidence to suggest that bromelain, one of the components, can influence fat cells and fat breakdown, this work was conducted in a mouse cell model. It is difficult to predict whether these results translate to human cells and to humans themselves,” she said. “I would err on the side of caution.”

Despite questions over the evidence base, marketing frequently boasts of impressive results, with double chins, “bingo wings” and “muffin tops” seemingly eradicated in a few sessions. One UK clinic’s website advertises the product as a quick fix, asking: “Diet and exercise not enough? Looking for quick, painless results that start showing in as little as 24 hours?”

Most of the promotions are from beauticians offering the treatment, but Lemon Bottle makes similar bold claims on its own official channels. On its Instagram page, Lemon Bottle says it is “completely safe”, has “no side effects” and delivers “instant results”.

Andrew Rankin, trustee of the Joint Council for Cosmetic Practitioners and an aesthetic nurse, said the marketing could appeal to those who were vulnerable due to body image issues “and in particular, young people”. He said no product was 100% safe, and there were still “a lot of unknowns”. “It may prove to be completely harmless, or we may start to see problems coming to the surface.”

Experts are also worried about Lemon Bottle’s regulatory status. Marketing materials show Sid Medicos has promoted the product as an alternative treatment for obesity. But it is currently classified as a cosmetic product, meaning there is no need for it to undergo the safety testing required for medical devices.

The status also means that Lemon Bottle can be freely administered by non-healthcare professionals, who are not subject to any professional oversight. While the government is considering introducing new rules, the beauty industry is currently unregulated, meaning there is no formal need for practitioners to undergo specific training. Last week, Lemonbottle courses were being offered to lay people for as little as £50, while training manuals and boxes of product were openly resold online.

While the jury remains out on Lemon Bottle’s long-term benefits and risks, the experts all agree that patients should be sceptical of grand marketing claims. Those considering fat-dissolving injections should seek treatment from an aesthetic doctor or healthcare professional who is trained and properly insured.

As for the bacon fat stunt, even Karimyan isn’t convinced. He says he tried it himself – leaving the rashers out for three days – but to no avail. Even if it were to work in some cases, he said the process of breaking down fat in the human body was different from that of breaking down bacon fat because different factors are at play, such as oxygen and blood supply. “It’s a marketing trick,” he said.

Lemon Bottle did not respond to requests for comment.