Urgent work must start to tackle the "endemic" level of abuse of special needs teachers, a new study has said.
Thousands of teachers suffer constant intimidation, threats and assaults by pupils, often on a daily basis, according to research by teaching union the NASUWT.
Three quarters of those who responded to a survey said they typically lost up to two hours of teaching time a day dealing with pupil indiscipline.
Most said their headteachers failed to use legal powers to discipline pupils, including searching those suspected of carrying offensive weapons, tackling bullying and exclusion.
Those who experienced abuse said school leaders were reluctant to act.
The NASUWT called for the decline in the number of special schools - where staff are more likely to be experienced in dealing with autism and behavioural problems - to be "reversed as a matter of urgency".
General secretary Chris Keates said: "This survey appears to show that not only is there an endemic level of abuse being directed at teachers working in specialist settings, there is also an unspoken understanding that such behaviours are to be expected as part of the job.
"There must be no expectation that teachers should have to tolerate assaults or abuse at work by virtue of the pupils they teach.
"These findings show that teachers' views and experiences of pupil behaviour are not being treated seriously and teachers have little confidence that their school will act appropriately to protect them from abuse."
Fewer than half of those who took part in the survey said they had received "timely" support after referring a pupil for a behaviour issue.
The survey found just 46 per cent of schools follow the legal duty to "tackle all forms of bullying" and only 30 per cent had arrangements to search pupils suspected of carrying offensive weapons.