Food allergies are caused by proteins, i.e. allergens. Testing for allergens is useful, however, it is not always possible to find out what the allergy is by testing for allergens. Because food allergies cause allergic reactions, there are three medical pathways, IgE-mediated, non-IgE-mediated, and mixed-mediated. The current medical methods used to check for allergens are all IgE checks, meaning that only food allergies caused by IgE can be detected by the test possibly, and the positive rate of this test is less than 20%. If one is allergic to eggs, a blood draw may only show positive results in 20% of patients. There are several methods of testing, with blood sampling for IgE and skin prick being the most common. If the blood is positive for IgE, it is evidence of a possible allergy. If the amount of IgE is found to be particularly high, (+ + +), (+ + + +), such as within 2 years of age to eggs found to be (+ + +) or more, the possibility of allergy to eggs is 95%, that is, it can be proved to be allergic to eggs; if 2 times found to milk (+ + + +), the possibility is 95%. The possibility of allergy to soybean and wheat if it occurs above (+ + +) is more than 80%, and it is based on different + to determine if it is allergic to this thing. However, if the skin prick has a packet, it does not completely indicate an allergy to a certain food. However, there is a very certainty that the skin prick is negative when it is definitely not allergic. However, 80% of negative blood draws contain the possibility of allergy. Therefore, it is important to fully understand the significance, value and guidance of IgE testing, as well as the significance of skin prick, when determining the choice of food allergy antigen testing.