Avoid the corniest
It all has to be based on how easy it is to trigger your allergic symptoms.
Just having a positive skin or blood test may not mean you have a clinical allergy. If you do, though, start by avoiding the most obvious: corn on cob, popcorn, cornbread, corn flakes, corn chips, corn syrup foods like soft drinks and other sweets, corn starch. Read labels and do your best. If still symptomatic, see doctor.