i actually have no idea but it was the same at my primary school, like you had to have your parents contact the admin office and they had to hold the painkillers for you. For a while i thought it might have been because they could be mistaken for hardcore drugs or you could get high off of them?
I’m exaggerating when i say the punishment was severe but like i suppose it would be bad if they spotted you? they never spotted my friends and I so it was fine. I just know they were banned from school grounds.
If you got cramps or a headache you just either sucked it up or went to the sick bay and got a hot pack. Pree shit i know.
tbh, i just had a dealer (so to speak) a chick in my class who always had a supply of pretty decent painkillers in her pencil-case (her mum was a nurse)