Food Allergy symptoms/reactions include the following: facial flushing, nausea, vomitting, hives, angiodema, trouble breathing, lowered blood pressure, itching skin, coughing, swollen throat, etc.
In addition to the symptoms that rsox34 posted, there are many others. Actually, a food allergy or sensitivity can mimic other diseases as well. I have food allergies, and when i eat an offending food, I will sometimes get anxiety attacks and irregular heart beat. They can also cause migraine headaches, and, believe it or not, even weight gain. Some folks wonder why they try and try to loose weight but nothing seems to work, well, sometimes it is what they are eating and when they stop eating that particular food, they loose weight.
Another note, some folks actually "crave" the very foods they are allergic to, it is strange, but, it almost like your body is "addicted" to that food. No one really know why however.
I have allergies to wheat, corn, soy, potatoes, peanuts, tree nuts and tomatoes. My symptoms were weight gain, inflammation, dry eyes, itching during exercise, asthma, swollen hands and ankles, headaches and itchy mouth. I think they vary quite a bit from person to person. I also get extreme hunger pains when I start to eat something I am allergic to if I start with an empty stomach.