Allergies are caused by an overactive immune system. The way to overcome them is to train the immune system by exposing yourself to low doses of the allergen. Doctors do this and it’s called allergen immunotherapy. Interestingly this has been done since 1911.
I used to be allergic to 100s (I could not even walk 1 meter of certain weeds and I would get blisters etc) of things until I moved away from my country 20+ years ago. I suddenly was allergic (as far as I know still now) to nothing; I accidentally came in contact with some of the worst allergens of old (as I live in nature since then) and they did nothing to our surprised. My wife who was allergic to seafood (passing out to needing epi levels) and that’s gone too, shortly after the move. I don’t know why; our doctor then didn’t know, but we chalked it up to stress; we went from depressing commute ratrace city jobs to sitting in a forest in nature doing whatever we liked. I work more hours now but they are stressless. Don’t know whatever is true, but one mistake I made was not moving earlier.
https://www.nature.com/articles/s41577-022-00786-1