Keep this in mind when you are reading the corn allergens list: the items on the list might not always be derived from corn, but all CAN be derived from corn. This is probably the hardest thing for those new to a corn allergy to understand!
For example, the common ingredient citric acid is not always from corn; it can be from fruit. Many manufacturers would love for you to believe their citric acid is from fruit, especially if it is a fruit product. A few years ago, I was wondering if I could drink Fruit H2O (flavored water), which had citric acid listed as one of the ingredients. I called the manufacturer (something I do not bother doing anymore), and I swear the customer service rep was offended that I even insinuated that there would be corn in their product. "I can assure you our product does not contain any corn!" was what she kept insisting. In turn, I kept insisting that I be told what the source of the citric acid was. Eventually, I managed to get information out of her that the citric acid was indeed from corn, but it had been processed so much that "there was no corn left in it." Huh??
The hardest part of shopping for a corn allergy is not knowing the ingredients of ingredients. For example, sour cream lists cream as an ingredient, but if you read the ingredients of cream, it can contain sodium citrate, which can be derived from corn and cause an allergy reaction. I have over time avoided more and more products simply because I do know what is in the ingredients and cannot trust the manufacturers anymore.