Allergic diseases are conditions in which a patient inhales or ingests substances containing allergenic components (called allergens or allergens, allergen) that trigger the body’s B cells to produce excessive immunoglobulin E (IgE). The detection of total IgE can be used to assist in the diagnosis of allergic asthma, seasonal allergic rhinitis, atopic dermatitis, drug-induced interstitial pneumonia, bronchopulmonary aspergillosis, leprosy, pemphigoid and certain parasitic infections.