People used to call Anika the Snap Queen. Between the ages of 19 and 21, she was “obsessed with Snapchat, to the point where I had 4,000 followers”. At the peak of her “tragic” behaviour, she reckons now – a year after quitting the image-sharing app – she was taking 25 selfies a day.

She liked the sense of having a platform, she says, with the average selfie getting 300 replies. “It was like, ‘Oh my God, I’m so popular – I’ve gotta show my face.’” But the filters were also part of the appeal. The Londoner had long been insecure about the slight bump in her nose. Snapchat’s fun effects, which let you embellish your selfies with dog ears, flower crowns and the like, would also erase the bump entirely. “I’d think, ‘I’d like to look how I look with this filter that makes my nose look slimmer.’”

Socialising in the real world, she would choose her seat to avoid being seen in profile. She recognises that this was irrational – “but it happens. I feel like we’re in a world where a lot of people are seen to be perfect, and so we try and reach that peak.”

Sometimes her followers would suggest meeting in person. “Then it would be like, ‘I have to look like my selfie.’” It was around this time, the height of her Snapchat obsession, that Anika started contacting cosmetic doctors on Instagram.

The phenomenon of people requesting procedures to resemble their digital image has been referred to – sometimes flippantly, sometimes as a harbinger of end times – as “Snapchat dysmorphia”. The term was coined by the cosmetic doctor Tijion Esho, founder of the Esho clinics in London and Newcastle. He had noticed that where patients had once brought in pictures of celebrities with their ideal nose or jaw, they were now pointing to photos of themselves.

While some used their selfies – typically edited with Snapchat or the airbrushing app Facetune – as a guide, others would say, “‘I want to actually look like this’, with the large eyes and the pixel-perfect skin,” says Esho. “And that’s an unrealistic, unattainable thing.”

A recent report in the US medical journal JAMA Facial Plastic Surgery suggested that filtered images’ “blurring the line of reality and fantasy” could be triggering body dysmorphic disorder (BDD), a mental health condition where people become fixated on imagined defects in their appearance.

Like Esho, Dr Wassim Taktouk uses non-surgical, non-permanent “injectables” such as Botox and dermal fillers to enlarge lips or smooth a bumpy nose. He recalls a client coming to see him in his cream-carpeted Kensington clinic, upset after a date made through an app had gone south. “When she’d met the man, he had been quite disparaging: ‘You don’t look anything like your picture.’”

The woman showed Taktouk the heavily filtered image on her profile and said: “I want to look like that.” It was flawless, he says – “without a single marking of a normal human face”. He told her he couldn’t help. “If that’s the picture you’re going to put out of yourself, you’re setting yourself up for disappointment.”

Why do we take so many photos of ourselves? A 2017 study into “selfitis”, as the obsessive taking of selfies has been called, found a range of motivations, from seeking social status to shaking off depressive thoughts and – of course – capturing a memorable moment. Another study suggested that selfies served “a private and internal purpose”, with the majority never shared with anyone or posted anywhere – terabytes, even petabytes of photographs never to be seen by anyone other than their subject.

With so much of life now lived online, from dating to job-hunting, recent, quality images of yourself are also a necessity – it is no wonder that Facetune (Apple’s most popular paid-for app of 2017) and the free follow-up Facetune2 have more than 55m users between them. Stav Tishler of Lightricks, the company behind them, says making airbrushing accessible has challenged “that illusion that ‘a perfect body’ exists … and levelled out the playing field”: “Everyone knows everyone is using it, supermodels and ‘everyday’ people alike.”

However, a 2017 study in the journal Cognitive Research: Principles and Implications found that people only recognised manipulated images 60%-65% of the time. Esho says the pervasiveness of airbrushing on social media means it can create “unrealistic expectations of what is normal” and lower the self-esteem of those who don’t use it: “It’s a vicious cycle.”

When the American Academy of Facial Plastic and Reconstructive Surgery surveyed its members in 2017, 55% of surgeons said patients’ motivation was to look better in selfies, up from just 13% in 2016.

Even novelty filters such as Snapchat and Instagram’s, as well as adding bunny ears or specs to your selfie, plump your lips, erase your pores and lift your jowls while they are at it. (Snapchat declined to respond on the record.)

“The first thing that any of these filters do is give you a beautiful complexion,” says Taktouk. “Your naso-labial [laugh] lines, from the nose to mouth, aren’t existent – but that’s not a human face. No one doesn’t have those. You can see them in children.” Clients still request their removal, and of “the tear trough” – the groove down from the inner corners of the eyes. “People wanting bigger eyes is another one – it’s just not possible.”

The filtered-selfie look is also reflected in demand for bigger lips and taut jawlines. Such so-called “tweakments” have exploded in recent years, thanks to their relative affordability and convenience. A “liquid nose job” using fillers might cost a few hundred pounds and takes instant effect, compared with the slow, painful recovery from a surgical rhinoplasty. Marla, 29, from New York, got her “perfect nose” last year while on her lunch break. “I went back to work feeling just so much more polished and confident – like I was even writing my emails better.”

Like Anika, she had always been bothered by the bump in her nose, religiously removing it from selfies; but she began exploring real-world options after a painful breakup. A list of pros and cons revealed that the potential risks – of her parents’ disapproval and “necrosis of the face” (“It’s very rare, but it’s definitely a thing”) – did not outweigh the benefits of having “the nose I create for myself on Facetune”.

The rise of fillers – anything from collagen and hyaluronic acid, which break down in a matter of months, to the permanent but riskier polymethyl methacrylate beads – has been accelerated by celebrity endorsements from the likes of the Kardashian clan. The removal and subsequent return of Kylie Jenner’s lip fillers have been followed with particular interest. Some doctors try to capitalise on this with “the Kylie package” for nose, jaw and lips, says Taktouk, disapprovingly. Ten years ago, his clients were deeply concerned with patient confidentiality; “Now, it’s ‘Do you mind if I Insta-story this?’ It’s not taboo any more.” He has seen lips advertised for £150 and noses for £200-£300. “And that’s one of the trickiest procedures of the lot.”

Fillers may be less invasive than surgery, but they are not without their risks, which range from uneven results and infection to vascular blockages and even blindness. Save Face, the UK’s largest register of accredited practitioners of non-surgical treatments, says almost 1,000 complaints were made in the year to October. Yet there is little regulation and no minimum age. “We have more protections for houses than we do children’s faces,” says Esho, who has campaigned for crackdowns. “It’s crazy.”

Even Marla – who documented her follow-up nose job in a short film for Vice, and does paid promotional work for cosmetic surgeons – says she would not encourage a young girl to do as she did. “I know that I love myself – that’s why I let myself get little tweaks – but it would really bother me if a young girl told me that she didn’t.”

Taktouk refuses to treat anyone younger than early 20s, but he says he has been contacted by 16- and 17-year-olds, sometimes for “preventative Botox” (“They haven’t even done A-levels yet”). Invariably it is via Instagram, where a reported 60% of users are aged between 18 and 24. The platform has become a marketplace for cosmetic procedures, with doctors showcasing their before-and-afters.

The process is as easy as “click-click-click, look at 10 bits of his work in the space of a minute, wow, let’s contact him”, says Anika. At the age of 20, she turned up at Taktouk’s clinic with photos of noses he had done and a video of herself with a Snapchat filter. “You know the one that kind of makes your face look like an alien’s? I was like, ‘This looks great – my nose looks so much smaller.’ Dr Taktouk was like: ‘This is not what is going to happen with filler.’” She laughs. “He told me to come back with my mum.”

Instead, Anika took a year out to consider her decision, weighing up fillers’ merits against surgical rhinoplasty. “Actually, I went through a phase of thinking, ‘No, I should try and love myself.’” How did that go? “I didn’t do rhinoplasty,” she says drily. “I guess that’s as far as I got.” By the time she returned to Taktouk’s clinic, aged 21, she had been brought “back down to earth”. He injected filler into the tip of her nose, evening out its line. She loved it instantly. “I feel like I just needed that to change me inside, so I could stop looking for perfection.”

When the filler eventually breaks down after about a year, she will repeat the procedure. “The most beautiful thing is when someone is happy from within,” she says; “as ironic as it sounds”, her new nose helped her to attain it. “I’m not itching to get anything else.”

There was a moment just after the procedure, though, as she was admiring her new profile, when she wondered aloud if her lips needed filling, too. They were one of her most prominent features; she had been called Fish Lips at school. Taktouk told her to stop being silly. “When you’re in that seat, it’s quite tempting,” she says. “Like, ‘What else can I do?’”

There is an obvious danger in trying to measure up to images when they are so far from reality – or even consistency. Non-filtered selfies are flipped, front cameras produce different results from back cameras, and there are even marked differences between models of phone. Just the distance from which we typically take selfies has a huge effect. A 2018 study found that a portrait taken from 30cm (12in) away rather than 1.5m (5ft) increases perceived nose size by about 30%. And that’s without the distorting effects of lighting and even makeup.

It prompts the question: which are you trying to correct, the image or the reality?

Anna, 40, from Malvern – another patient of Taktouk’s – admits to having once been “fixated” on her laugh lines. “The photos exacerbate it, making it look worse, then a filter can make it look amazing. You’re unsure of what you look like.”

Ever since she was young, she has struggled with the discrepancy between how she sees herself in the mirror, and how others see her. Once, she downloaded an app that claimed “to show you how you really look”. “It used to horrify me, and make me feel terrible about myself. But these are conversations you can’t really have, because you do sound self-absorbed and you’re leaving yourself vulnerable.”

She is more self-confident now, which she attributes both to age and the occasional self-esteem boost of Botox or filler. “I’m quite realistic now, whereas in the past I’ve driven myself crazy.”

For Taktouk, referrals from social media make it harder to safeguard patients’ mental health. His background as a GP has helped him to spot red flags, such as badmouthing other doctors, insisting on flaws that aren’t there, and in-depth knowledge of treatments: “I’ve had someone come in here and draw the lines on their face themselves.” But, he adds, “I’m sure some will have slipped past without me realising” – and even if Taktouk refuses to treat them, someone else will.

Over the weekend it was reported that Superdrug (which began offering Botox late last year) has agreed to introduce mental health screening for people seeking Botox, following criticism from the NHS for not conducting “medically responsible” checks. Taktouk says far more industry-wide regulation is needed, before there is a headline-grabbing tragedy and apps become even more transformative. He points to one called Retouch Me, which superimposes six-packs on to swimsuit pictures. “I saw it and thought, this is the new wave of what we’re going to get in: ‘Make me look like this.’”

Seeking unnecessary and unrealistic cosmetic procedures in fact supports a diagnosis of BDD, present in 2% of the population (and equally common in men and women). Dr Neelam Vashi, co-author of the American article that linked BDD to selfie dysmorphia, says further study is needed to establish whether intensive selfie-taking could trigger BDD – but it does resemble one of the main four diagnostic criteria: compulsive mirror-checking and other repetitive behaviours and thoughts.

The onset tends to occur in adolescence, though people with the condition may not seek help until 10 years later. The general rule, says Professor David Veale, a consultant psychiatrist at the Maudsley hospital in south London, is that you can “think about your appearance for an hour a day before it becomes a disorder” – but for a diagnosis, it must be accompanied by significant distress or inability to function normally. People with BDD take selfies because they are convinced “that they are hideous”.

In 2014, then 19-year-old Danny Bowman from Northumberland was reported to be “Britain’s first selfie addict” after being interviewed about his experience of BDD. His problems had begun four years before, when he was rejected by a modelling agency at the same time as he was being bullied at his new school and on Facebook. “For me, it was confirmation that I did look ugly.”

Bowman was soon spending hours before the mirror, slathering himself in acne cream and moisturiser and monitoring a steady stream of selfies for real-time improvement. After three months he dropped out of school, and the selfie-taking increased to hundreds a day. “I was trying to see some gradual improvement, and take that photo that I was pleased with. I was just trying to get that relief, and I couldn’t get it. There wasn’t a perfect photo. There isn’t a perfect photo.”

After six months of being housebound, consumed by his daily rituals, he tried to kill himself. “A lot of people say looking at themselves in the mirror probably makes them feel insecure, but imagine scanning through 200 pictures a day. I was just exhausted. I felt like there was no way out.” His mother – like his father, a mental health professional – found him in time and he was diagnosed with BDD. Part of his 12-week treatment involved restricting access to his phone.

Now 24, Bowman is studying at the University of York and campaigns on issues related to mental health and positive body image. He has raised concerns about the impact of Instagram with friends he sees “posting photographs of themselves every other day, Facetuning themselves, making themselves look unlike the way they look. That was me, but on an amplified scale.” They have reacted defensively, he says. “It has become such a normal thing that people don’t see what they’re doing as abnormal.”

He very rarely takes selfies now. “I just don’t feel the need to do it.”

• The Body Dysmorphic Disorder Foundation can be found at bddfoundation.org

• In the UK the Samaritans can be contacted on 116 123. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is on 13 11 14. Other international suicide helplines can be found at www.befrienders.org.