Members of public service union Unison are already engaged in a work to rule in a dispute over the medical care of pupils.
Now the union is threatening to take "discontinuous strike action" from the end of October, which could see classrooms operating without key staff such as pupil support assistants, instructors and care workers.
Unison officials claim the staff, who support the most vulnerable pupils, are not contracted or paid enough to carry out extra duties - which include supervising the administration of drugs for pupils with medical conditions.
However, Glasgow City Council says workers have been carrying out the duties for years and are given training and extra payments.
The industrial action has already led to a disabled boy, who was born without a nose, missing weeks of school.
Unison said last night that attempts to resolve the dispute with the council had failed so far, adding: "We now intend to call members to take part in further industrial action."
However, Stephen Curran, the council's executive member for education, said: "My hope is that members will not support this call to action which will stop our most vulnerable children getting to school.
"Throughout this dispute we have listened to their concerns and have offered to improve the pay of support staff. It is clear that Unison is not prepared to agree a compromise which would be in the best interests of their members."
Both sides will meet today.