Giving young people Botox treatment may restrict their emotional growth, experts warn.
Writing in the Journal of Aesthetic Nursing, clinicians say there is a growing trend for under-25s to seek the wrinkle-smoothing injections.
But the research suggests "frozen faces" could stop young people from learning how to express emotions fully.
A leading body of UK plastic surgeons says injecting teenagers for cosmetic reasons is "morally wrong".
Botox and other versions of the toxin work by temporarily paralysing muscles in the upper face to reduce wrinkling when people frown.
Mimicking to learn
Nurse practitioner Helen Collier, who carried out the research, says reality TV shows and celebrity culture are driving young people to idealise the "inexpressive frozen face."
But she points to a well-known psychological theory, the facial feedback hypothesis, that suggests adolescents learn how best to relate to people by mimicking their facial expressions.
She says: "As a human being our ability to demonstrate a wide range of emotions is very dependent on facial expressions.
"Emotions such as empathy and sympathy help us to survive and grow into confident and communicative adults."
But she warns that a "growing generation of blank-faced" young people could be harming their ability to correctly convey their feelings.
"If you wipe those expressions out, this might stunt their emotional and social development," she says.
The research calls for practitioners to use assessment tools to decide whether there are clear clinical reasons for Botox treatment.
Several assessment scales exist that take into account how thick the skin is, how sun-damaged it appears, and the depth of any wrinkles, but experts warn that some Botox clinics are putting financial gain first.
Ms Collier calls on therapists to spend time helping young people boost their confidence rather than reaching for injections.
She adds: "Though most of the effects of the toxin are temporary, research suggests the muscles don't fully recover from injections.
"We really need to understand the consequences of starting treatments too soon."
Dr Michael Lewis, a researcher in psychology at Cardiff University, says: "The expressions we make on our face affect the emotions we feel.
"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."
Rajiv Grover, president of the British Association of Aesthetic Plastic Surgeons, says: "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."
Ms Collier's research will be presented at the Clinical Cosmetic and Reconstructive Expo in October.