I know this may sound like a stupid question but I've been idly wondering after seeing how common allergies seem to be these days, and research hasn't revealed much.
I'm thinking like in the Medieval Period. Were some people allergic to milk or eggs for example? Would it just be the case that lots were allergic, like today, but severe sufferers would have died and the rest would have just had to put up with it?
Also things like hay fever, would some farmers or farmer's children have had it? Or would it have been rare because they spent so much time outside and so their immune systems could cope with it?