Name-calling is more devastating for children's self-confidence than physical bullying, a study suggests.
All bullying is traumatic and stressful, a study found
Dr Stephen Joseph, a psychologist at Warwick University, found verbal abuse had a large and ongoing impact on children's self-esteem.
The study, which assessed 331 pupils in England, found 40% had been bullied at some time.
It also revealed one-third of bullied children suffered significant levels of post-traumatic stress.
Dr Joseph said: "This study shows bullying, and particularly name-calling, can be degrading for adolescents.
"Post-traumatic stress is an anxiety disorder that can develop after exposure to a frightening event or ordeal in which physical harm occurred or was threatened.
"Research clearly suggests that it can be caused by bullying.
"It is important that peer victimisation is taken seriously as symptoms such as insomnia, anxiety and depression are common among victims and have a negative impact on psychological health."
The research paper examines the levels of post-traumatic stress experienced and the impact of bullying on the self-worth on victims.
A "victim scale" was devised to assess the experience of physical victimisation, verbal victimisation, social manipulation and attacks on property.
All types of bullying resulted in lower self-esteem, but social manipulation, such as excluding the victim from taking part in games, was more likely to lead to post-traumatic stress.
Verbal taunts typically led to lower self-worth.
The study also suggests verbal bullying or social manipulation can lead to victims feeling helpless and lacking control over their own feelings and actions.
Those who felt that power and control lay with the bully, rather than internally, were much more likely to suffer from post-traumatic stress or lower self-worth.