I became allergic to corn (and several other foods) in 1990 after a mysterious viral illness. At that time, I developed breathing problems and a terrible itchy rash all over my body, for months. I was so itchy I couldn't sleep, even on huge doses of antihistamines. My allergy to corn was diagnosed by an elimination diet: for a month, all I ate was lamb, white rice, and green grapes – since I am not allergic to any of these things, the rash and asthma symptoms, etc. went away. Once I was symptom-free, I added foods back one at a time, keeping a detailed diary of all their ingredients. Corn turned out to be one of the things that causes me problems.
I know that I am still allergic to corn because I still have allergic reactions after accidentally (i.e. negligently) consuming products containing corn on occasion – plus, I get an itchy throat and restricted breathing whenever I smell popcorn. However, I have outgrown allergies to tomatoes, peppers and strawberries in the last two years, and I have an uncle who outgrew a corn allergy. I hope to follow in his footsteps one day!