Most of the schools in our area will not allow any known allergens in the schools at all. I'm fortunate that all of my allergies are all bug/insect related. I've been prescribed an epipen but have been advised to only use it if I have difficulty breathing. I've been very lucky that all of my reactions have been very localized swelling so far.
But yes, if you have allergies that require an epipen, you need to go to the ER upon use of the epi.