hyperreactivity

Hyperreactivity refers to an exaggerated or heightened response of a tissue or organ to a stimulus beyond what is typical for a given individual. It is not a disease in itself but a functional state that can occur in various organs and conditions. The term is often used in fields such as respiratory medicine, dermatology, and immunology, and may overlap with the broader concept of hypersensitivity.

In the respiratory system, airway hyperreactivity describes excessive narrowing of the airways in response to irritants or bronchoconstrictor challenges, and is a core feature of asthma and allergic airway disease.

In the skin and mucous membranes, hyperreactivity can manifest as exaggerated inflammatory or allergic responses to allergens, irritants, or mechanical stimuli, as seen in contact dermatitis or urticaria. Ocular or gastrointestinal hyperreactivity is also described in certain disorders.

Mechanisms include immune-mediated processes such as IgE-dependent mast cell activation with release of histamine and other mediators, eosinophilic inflammation, and heightened neural responsiveness or central sensitization.

Assessment relies on functional tests and clinical history. In airways, bronchial or methacholine challenge tests measure the degree of hyperresponsiveness; skin tests and specific IgE assays support an allergic basis. Management aims to reduce exposure to triggers and to control inflammation with pharmacotherapy, including bronchodilators, corticosteroids, and allergen immunotherapy for appropriate cases.