Teenagers are undergoing plastic surgery to look like they do in their filtered selfies - and it may be a sign they are suffering from an underlying mental health condition.

In addition to unicorn horns and dog ears, Snapchat and Instagram also offer perfecting filters that smooth skin, thin your face, and change your eye colour - photo-editing technology that has resulted in a new mental illness scientists are calling “Snapchat dysmorphia.”

“A new phenomenon called ‘Snapchat dysmorphia’ has popped up, where patients are seeking out surgery to help them appear like the filtered versions of themselves,” said Dr Neelam Vashi, director of the Boston University Cosmetic and Laser Centre.

The study, published in JAMA Facial Plastic Surgery Viewpoint, found apps like Snapchat and photo-editing Facetune are to blame - as they allow selfies to achieve a level of physical “perfection” previously seen only in celebrity or beauty magazines.

According to plastic surgeons and researchers, patients are no longer bringing in photos of celebrities, they are bringing in pictures of their selfies - edited to look like perfect versions of themselves.

Dr Vashi said: "A little adjusting on Facetune can smoothen out skin, and make teeth look whiter and eyes and lips bigger. A quick share on Instagram and the likes and comments start rolling in."

Now millennials are trying to replicate the perfection in real life by seeking out treatments that contour cheekbones, straighten or reduce nose size, or make a person look slimmer.

As these images become the norm on social media, and in real life, the idea of what is attractive worldwide also changes - which can affect self-esteem and trigger body dysmorphic disorder (BDD) or Snapchat dysmorphia, a term coined by Dr Tijion Esho, a cosmetic doctor.

BDD is an excessive preoccupation with a perceived flaw in appearance often characterised by people going to great - and at times unhealthy - lengths to hide their imperfections.

The mental illness, classified on the obsessive-compulsive spectrum, is surprisingly common, affecting one in every 50 people - and growing, as millennials are influenced by what they see online.

Dr Esho, who will turn away patients who seem overly-obsessed with resembling filters, previously said: "We now see photos of ourselves daily via the social platforms we use, which arguably makes us more critical of ourselves. Patients using pictures of celebrities or Snapchat-filtered versions of themselves as reference points is okay.

"The danger is when this is not just a reference point, but it becomes how the patient sees themselves, or the patient wants to look exactly like that image."

And these filtered selfies can be even more dangerous for people with BDD.

Dr Vashi said: "Filtered selfies especially can have harmful effects on adolescents or those with BDD because these groups may more severely internalise this beauty."

Snapchat is reportedly to blame for the rise (Stock)

One survey of plastic surgeons found 55 per cent last year reported seeing patients who wanted to improve their appearance in selfies - in comparison to the 13 per cent the American Academy of Facial Plastic and Reconstructive Surgeons reported seeing in 2013.

This is coupled with the reported increase in plastic surgery patients younger than 30.

Rather than going under the knife, Dr Vashi recommends that people suffering from BDD seek psychological interventions such as cognitive behavioural therapy - as surgery can worsen underlying BDD.

"Filtered selfies can make people lose touch with reality, creating the expectation we are supposed to look perfectly primped all the time,” said Dr Vashi. "This can be especially harmful for teens and those with BDD, and it is important for providers to understand the implications of social media on body image to better treat and counsel our patients."

Filters are convincing teenagers to get plastic surgery (Stock)

The emergence of Snapchat dysmorphia comes after previous studies found social media negatively impacts self-esteem and increases the risk of mental health issues.

In a 2015 report from the Office for National Statistics, more than a quarter of teenagers who use social media for more than three hours a day were found to have problems related to mental health.

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For patients who do display symptoms of BDD, the researchers and doctors recommend additional screening to check for underlying problems.