Ex-teachers have said the strains of the job have caused them mental health problems.
A survey by online tutoring agency Tutor House questioned 2,276 of its site tutors who were formerly teachers and found 99 per cent would never return to teaching.
Nearly two thirds (62 per cent) had suffered mental health problems that they blamed on having been a teacher.
Among those who had suffered mental health problems, 52 per cent cited anxiety, 27 per cent depression and 21 per cent chronic stress.
Asked why they left the profession, 68 per cent blamed unmanageable workloads, 21 per cent pay and 11 per cent health reasons.
Tutor House founder Alex Dyer said: “These survey results are worrying and shocking, the teaching industry as a whole needs to take better care of its staff. Nobody should be suffering from poor mental health because of their work.”
He said pupils would quickly realise that a teacher was suffering from stress-related health problems, “and this is no good for anyone”.
Mr Dyer said the system of constant teacher assessment and appraisal should be stopped and their workloads reduced.