Overview of Allergic and Atopic Disorders By James Fernandez, MD, PhD, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University Reviewed / Revised Oct 2022 View Patient Education Classification of Hypersensitivity Reactions Etiology Pathophysiology Symptoms and Signs Diagnosis Treatment Prevention Key Points More Information Topic Resources Latex Sensitivity Oral H1 Blockers Intranasal Corticosteroids Intranasal Mast Cell Stabilizers Overview of Type I Hypersensitivi... Overview of Type II Hypersensitiv.. Overview of Type III Hypersensiti... Overview of Type IV Hypersensitiv.. Allergic (including atopic) and other hypersensitivity disorders are inappropriate or exaggerated immune reactions to foreign antigens.