I was a school teacher then a supply teacher - at the school I taught in (a 'top' performing school btw) pictures were on the wall of the staffroom taken in year 7 that stayed there for years. I occasionally looked at the pictures and picked out pupils in my classes, though I would not have had a hope about who was allergic to what.
Nothing else was said to me on the subject of allergies. I had no list, no info, no guidance.
As a supply teacher I turned up at the start of the day, got my paperwork, found the classroom with the help of a map and did my best to control the class and get some work out of them 
Allergies? No clue. As a supply you turn up, check the register, set the work, police the little darlings, let them run free when the bell goes.
So yes, poor boy, and poor teacher too 