Young people who undergo Botox treatment could suffer stunted emotional growth, experts have warned.
According to research published in the Journal of Aesthetic Nursing, there is a growing trend for people under the age of 25 to seek cosmetic facial injections, which could stop them from learning how to fully express emotions.
Nurse practitioner Helen Collier, who carried out the research, said contemporary celebrity culture and reality TV shows are increasingly driving young people to seek the "inexpressive frozen face".
"As a human being, our ability to demonstrate a wide range of emotions is very dependent on facial expressions," Collier told the BBC.
"Emotions such as empathy and sympathy help us to survive and grow into confident and communicative adults. If you wipe those expressions out, this might stunt their emotional and social development."
Confidence beats Botox
Researchers urged practitioners to use assessment tools to decide whether or not there are clear clinical reasons for Botox treatment.
Collier also called on therapists to spend time helping young people to boost their confidence instead of opting for facial injections such as Botox that temporarily paralyse muscles in the face to reduce wrinkling when people frown.
"Though most of the effects of the toxin are temporary, research suggests the muscles don't fully recover from injections," Collier added. "We really need to understand the consequences of starting treatments too soon."
Rajiv Grover, president of the British Association of Aesthetic Plastic Surgeons, said: "Injecting teenagers with Botox for cosmetic purposes is morally wrong and something that no ethical practitioner would do. This can only exacerbate body image issues at a vulnerable time."
Dr Michael Lewis, a researcher in psychology at Cardiff University, added: "We smile because we are happy, but smiling also makes us happy.
"Treatment with drugs like Botox prevents the patient from being able to make a particular expression and can therefore have an effect on our learning to feel emotions naturally."