A person will never know if they are allergic to a certain type of food unless they have eaten the food allergen itself. It takes a certain amount of food for the reaction to take place and trigger a symptom.
Allergies to food are commonly dealt with by the avoidance of the allergy-causing food. When the allergen (the one that causes allergic reactions) has been recognized, the patient is then advised to eliminate it from his or her diet. This is achieved by revolutionizing the food prepared and reading carefully food labels on food products. A specific instruction when ordering food also helps avoid allergic mishaps when eating out.
There have been a lot of studies about food allergy that involves patients having asthma. You can easily see the symptoms after a couple of hours after eating a certain kind of food. Asthma and eczema are associated with atopic patients with allergies in food.