An IgE (Immunoglobulin E) test along with skin scratch test is performed on a patient to know whether they are allergic to certain food items. In this case, we will be checking whether a person is allergic to coffee or not. An IgE test measures the blood level of IgE, one of the antibodies present in our bodies. Antibodies are made by our immune system in order to protect our body from antigens like Bacteria, Virus, allergens. These antibodies are mostly found in lungs, skin and mucous membranes. Scratch test on the skin is performed to confirm if the person is allergic to that particular allergen or not.