Fighting Respiratory Infections with Oil of Oregano?

I live in the Sonoran Desert, and have heard that a drop of Oil of Oregano under the tongue before going out into the wind in AZ can help prevent Valley Fever. A resident in my community actually thinks it helped save his life! However, I am allergic to Benedryl or sure, and possibly other antihistimines, and read here that is can also act as an antihistimine, so now I don't know whether to try it or not. Anyone have any feedback in this area? I "don't do spicy" foods, so would probably want to use the capsule form, if it comes in that small a dose. Thanks, Maureen