Lip filler is no longer beauty’s dirty little secret. The procedure – which consists of injecting hyaluronic acid into the lips to make them appear fuller – was once mainly associated with A-list clientele. Now it is arguably as common as a brow wax and offered in multiple aesthetic clinics and beauty salons up and down the UK.

Results can be transformative or cleverly discreet. Depending on the experience of your chosen practitioner and the amount of lip filler you’d like, the price varies from £300 to upwards of £750. Top-ups are recommended every four to six months and filler removal is only possible via an additional ‘dissolving’ procedure. In other words, lip filler is a serious commitment. It’s no wonder, then, that those who regularly get filler might choose to cut corners.

At present, filler is largely unregulated in the UK and the treatment can be done by anyone. Many practitioners do not have the relevant training and insurance, leading to botched and dangerous results. But something even riskier is gaining traction among lip filler lovers, and the side effects are a major cause for concern. Recently women have been taking filler into their own hands by purchasing DIY lip filler pens online. A quick internet search uncovers many of these tools, the cheapest just £55 with refills as little as £12.50 – a snip of the price of a professional lip filler procedure. Shockingly, you do not need to be a trained aesthetician to buy one – anyone can. Even more surprisingly, you can perform the procedure on yourself in the comfort of your own bathroom.

Judging by website reviews, it takes just a couple of minutes to administer the filler and there is neither pain nor downtime. But knowing how these devices work is key to understanding the multiple dangers. “Lip filler pens are slightly different to the traditional dermal fillers we use in clinic,” says Dr Emma Wedgeworth, consultant dermatologist and British Skin Foundation spokesperson. “They are pen-like devices which don’t use normal needles. Instead they use jet injection technology to deliver hyaluronic acid or other substances into the top layers of the skin.” Dr Tijion Esho, cosmetic doctor and owner of Esho Clinic in London and Dubai, explains that the jet injection is essentially pressurised air, which forces dermal filler through the surface of the lip.

If you aren’t wincing yet, the many online tutorials showing people how to use lip filler pens bought over the internet will send shivers down your spine. The enormous device resembles an ear piercing gun and shoots out with a loud click, depositing filler into lips and other areas of the face. Often the force is so great that it takes the user by surprise and jolts them backwards. Lips emerge much fuller but appear swollen, bruised and red. These immediate results mirror professional lip filler treatments but the long-term side effects recently discovered by experts are horrifying.

“We are only just beginning to learn about the complications of these devices because they are relatively new to the market,” says Dr Wedgeworth. “The devices claim that the hyaluronic acid is only delivered to the top layers of skin and therefore are relatively safe, but the high pressure at which the product is delivered can cause complications.” Problems include blocked blood vessels (which results in reduced blood flow to the skin of the lips and significant damage to the skin) as well as bruising, swelling and lumpiness, adds Dr Wedgeworth.

Medical aesthetic clinician Dr Yusra Al-Mukhtar says such devices will inevitably cause trauma due to the sheer force. “I saw one patient who attended with photos of bruising and multiple clumps of dermal filler above the muscle of the lip. This caused bumps every time she smiled.” Infection is also common as DIY procedures are often performed without any real regard for sanitisation, unlike in clinic, where syringes are sterile.

Scars and disfigurement are the main side effects that Dr Esho has seen in clinic. Patients often come to the trusted aesthetician to reverse botched treatments. “The pressure is never enough to place the product in the correct layer of the lip,” he says. “Many times, it just sits on the superficial surface. I see cases in my clinic where the product was unable to push deep enough into the lip, leaving behind multiple lumps or what I call lip filler cysts.” Dr Esho recalls recently assessing a blocked blood vessel, which almost caused a patient to lose her lip entirely.

The aftermath of DIY lip filler pens is potentially life-changing, so why are tools like these so readily available online? According to Dr Wedgeworth, lip filler pens are not deemed to be medical devices and do not need a prescription. “That said, while the manufacturers try and ensure they are only sold to reputable clinics, it doesn’t always happen,” she adds, which explains why a quick search unearths numerous questionable sellers who provide little to no information on correct procedure or the risks involved. Websites we came across touted the tools as fast, effective and safe – which was refuted by both experts we spoke to for this piece.

Dr Wedgeworth believes that lip filler pens should be reclassified as medicines, which would enable tighter regulation, while Dr Esho thinks they should be banned altogether. “Dermal fillers are medical devices and should only be handled and used by medical professionals,” Dr Esho says. “The public lack the knowledge to know how to use these and more importantly do not know how to treat things if they go wrong.”

Dr Esho has campaigned for better regulation but ultimately it is the government that needs to take note. “In the wrong hands, tools like these can do so much damage, not only physically but also mentally,” he continues, as some results may end up botched. “We do need better education but fundamentally, we need laws in place to support this and protect the vulnerable,” Dr Esho adds.

It is evident that the risks associated with DIY lip filler pens largely outweigh the benefits and under no circumstances should anyone attempt something as risky as lip filler – either in pen or needle form – at home. There is no denying lip filler’s popularity, though, and if you are set on having the procedure, doing your research is paramount. “If you want filler done professionally, be incredibly careful who you go to,” says Dr Wedgeworth. “Save Face is an organisation which has been set up to find government-approved, accredited nonsurgical cosmetic practitioners, who work to approved safety standards.”

Dr Esho also hits home the importance of a consultation with a registered medical professional before booking anything. “Make sure you understand the full risks before you undertake the procedure,” he says. “Ensure your practitioner is insured, ask to see examples of their work and even discuss experiences with past patients.” Dr Esho recommends medical clinics above all other settings, with a doctor, dentist or nurse present. “Make sure you have a follow-up appointment,” he concludes, “and always log an emergency contact – just in case things do go wrong.”