To a large extent, allergies didn't exist until recently. They're a product of the modern world.
About a hundred years ago, doctors were aware of allergies, but they tended to afflict the rich only (because the rich had lifestyles closer to what everyone has now). The main treatment was avoiding the allergen. This sometimes meant moving to someplace that didn't have that particular pollen, or whatever (remember, these are rich people, they can buy a house in Flagstaff just because Junior gets stuffed up).
In ancient times I imagine there were still a few people with allergies, but I've never seen a mention of the concept directly. Someone with a severe enough reaction probably died of a "fit." Lots of people died of fits.