Many agree that local foods like fruits, veggies, and even cows milk will help because all those foods will carry traces and various forms of environment allergens due to being produced in the area. They build up natural immunity.
Herbal teas are a must; with local, raw honey. The honey will also carry the allergens and be a quicker way to build up immunity.
Cut back on sugars. They inflame the immune system even more.
Lots of sleep; cool compresses on head and eyes; Take a full day every few to stay indoors as much as possible to 'recover'.
I moved for college to a state with terrible, terrible environmental allergens. People who never have had allergies react strongly as soon as moving.... It took a couple years, but now I can limit my allergy meds to a month period during the 'start' of fall....mid-August to early September, and can go the rest of the year sans allergy meds. But it took all of the above steps until I had built up enough of a natural immunity and a healthier immune system to do it. Otherwise, I took meds most of the year...unless there was ice on the ground.