The pupils get as far as the entrance hall of Falcone di Bergamo high school, but as soon as they enter the classroom they are overcome with a "mystery illness", with symptoms including breathing problems and rashes, Corriere della Sera reported.
Just eight pupils are affected, with five of those experiencing severe symptoms, the newspaper said.
The bizarre reaction to school has baffled teachers and medics since October 7th, when at first two schoolgirls were hit with symptoms upon entering the classroom.
The symptoms - which mysteriously disappear after they leave the classroom - soon spread to two of their classmates, before affecting four others in a neighbouring classroom.
Environmental tests have been carried out on the rooms, as well as medical tests on the students, but experts from the local health services have so far been unable to find a cause, Corriere reported. External factors have also been ruled out.
There have also been cases of other students fainting in the school, but it is not clear whether the two problems are connected.
“We've seen it happen several times,” one student in the second year told the Corriere della Sera.
“There's nothing wrong with them when they come in, then as soon as they enter the classroom they start to have difficulty breathing; they say their throats swell up, and after a little while they start to itch all over their bodies.”
They are forced to stay as far as possible from the classroom, though their fellow students are able to continue the lessons without problems.
“For now, all we know is that it's some kind of allergic reaction,” headteacher Enzo Asperti told Corriere.
He explained that the school had followed all the directions given by the local health authority, including cleaning the school and keeping it aired as much as possible.
The school is considering teaching the afflicted students over Skype if symptoms persists.