A one-size-fits-all approach to treating teenagers with anxiety problems may be putting their futures at risk, a study suggests.
University of Reading psychologists say current childhood therapies are simply being adapted for teenagers.
But they argue that adolescents face distinct issues and call for tailored treatments to address them.
Charities say adolescent and child mental health services are at breaking point and need to change.
Anxiety problems affect some 300,000 children and adolescents in the UK.
Young people are diagnosed with anxiety disorders if anxious feelings seriously affect their everyday lives - for example preventing them from going to school or attending social events.
Those who are offered specialist help are often given cognitive behavioural therapy (CBT) - a talking treatment that involves helping people understand triggers for their anxiety and encourages them to change the way they think about and behave in anxiety-inducing situations.
The study, published in the Journal of Affective Disorders, compared the symptoms of 100 children (aged six to 12 years) with those of 100 teenagers (13 to 18 years) referred for CBT in Berkshire.
Some were given an online version of cognitive behavioural therapy, where participants read about fictional characters and their responses to situations that could make them anxious.
Researchers found teenagers with anxiety disorders were more likely to have serious symptoms and to have anxiety surrounding social situations.
Adolescents were also more likely than children to suffer from depression or low moods.
But lead researcher Polly Waite said: "We found teenagers were often receiving treatment designed for younger children which is then simply being adapted or made cooler.
"For example, some of the pictures used in the online therapy were simply changed from teddy bears to images of grungy teenagers."
Dr Waite added: "Many teenagers therefore will be receiving treatment that does not specifically address symptoms that occur in adolescence.
"This may mean they have poorer treatment outcomes, putting their futures at risk.
"By targeting more effectively, we could stop teenagers developing mental health problems, leading to fewer suicides and incidence of drug and alcohol problems."
Researchers say people designing the therapies need to work closely with adolescents to find out what types of words and images are most acceptable to them.
Lucie Russell, of the charity YoungMinds, said: "It is absolutely right we recognise that adolescents have a different set of needs, experiences and challenges to younger children and therefore it is vital that treatments are developed for anxiety that work specifically for them.
"Child and adolescent mental health services are at breaking point with too few resources to meet an ever increasing demand.
"It is worrying but not surprising that sometimes adolescents are not able to receive specific treatment for their needs.
"This needs to change if we want to stop the slide of many young people from children's to adult mental health services because their problems weren't addressed appropriately when they first started to suffer."