Researchers at the University of the West of England found 75% of 15 year olds questioned said they were upset by teasing about the way they looked.
Of 1,000 teenagers questioned, 20% said they played truant because of worries about their appearance.
Even more - 31% - said their lack of confidence about the way they looked stopped them taking part in classroom discussions.
Confidence
The study was carried out by Dr Emily Lovegrove, who said: "This research shows that teasing and bullying about appearance undermines global self-esteem and affects academic confidence.
"But if we can teach social skills to deal with psychological bullying - which is the most common form - then this may stop physical bullying from ever starting.
"Once young people have learned these strategies they are easily adaptable for use in other types of confrontation."
Body language
As part of the study Dr Lovegrove developed a programme to help teenagers cope with bullying related to their appearance.
About 200 12 and 13 year olds were given lessons on how to deal with bullies, including the importance of body language.
Among those children, Dr Lovegrove said perceived levels of bullying fell by about two-thirds in the six months after the course.
Dr Lovegrove is calling for funding for self-help books for children and teenagers who are teased about their appearance and for courses to raise awareness among teachers.
The research was funded by Changing Faces, a charity which supports children and adults who are disfigured.