Could you be alergic to something and have a small reaction?

Depends: We need a few more details. A small sniff of cat fur might just give you a sneeze. But a spoonful of peanut butter could send you to the ER. Some codeine cough syrup might make your nose itch, but continuing on a sulfa antibiotic while ignoring early Stevens Johnson Syndrome might land you in the burn unit in renal failure. I've see all of these. Details matter.