How do you know if you have a ketchup allergy?

Allergic symptoms: Symptoms of food allergies can range from itching of the lips, tongue, palate or throat to GI upset with nausea, vomiting, cramping, bloating, or diarrhea, to headache, nasal congestion, runny nose, itchy eyes, puffy eyes, itchy ears, itchy skin, hives, rashes, to cough, asthma, flushing, shock or rarely, joint pains. One could be tested to components like tomato, or do a prick test w/the food.