Allergies are the immune system's overreaction to a harmless foreign substance that enters the body, such as pollen, dust, or animal dander. These substances that cause the reaction are known as allergens. When an allergen enters the body and is detected by the immune system, the immune system reacts by producing antibodies to fight the allergen. These antibodies release histamines which result in symptoms commonly associated with allergies, such as runny nose, irritated eyes, sneezing, or swelling (AAFA, 2022).

Allergies typically develop in childhood, but may develop or change over time. Allergic reactions that cause symptoms include allergic rhinitis (CA08.0), asthma (CA23), anaphylaxis (4A84), eczema (EA80), and hives (EB05).

Diagnosis of allergies often involves a diagnostic allergy test accompanied by a consultation with an allergist. Allergy testing can be completed by skin prick test (SPT) or an IgE blood test, such as the ImmunoCAP ISAC. SPTs are conducted in a physician's office and expose your skin to various allergens to identify any reactions. IgE tests are blood draws that identify and measure the antibodies in your body that fight allergens.