skin disorders
Overview of Hypersensitivity and Reactive Skin Disorders
Introduction
The Overview of the Immune System plays a vital role in maintaining the health of all the tissues of the body. The immune system reacts to invaders, such as microorganisms, foreign substances, or cancer cells, and triggers inflammation to attack these invaders. Usually the immune system reaction protects the body and aids healing. However, sometimes the immune system overreacts, or the reaction is misdirected at healthy tissues and causes intense inflammation and damage. These abnormal immune system responses are called hypersensitivity reactions. Some hypersensitivity reactions are called allergies, especially when they occur after exposure to substances that are usually harmless to most people. Hypersensitivity reactions can involve the skin and cause disorders such as the following: Drug Rashes None Erythema Multiforme None Erythema Nodosum None Granuloma Annulare None Keratosis Pilaris None Panniculitis None Pyoderma Gangrenosum None Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) None Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) None Skin can be involved in a variety of immune system reactions, many of which cause rashes. The word "rash" refers to changes in skin color (such as redness) and/or texture (such as bumps or swelling). Many rashes itch, such as those that often develop after an allergic reaction, but some rashes are painful or cause no sensations. Sometimes an immune reaction is triggered by an infection, substances a person touches or eats, or by a drug a person takes, but many times doctors do not know why the immune system reacts to produce a rash. Rashes in Children , whereas others almost always occur in adults. Although many skin disorders are caused by the immune system's reaction, some are caused by things that directly affect the skin without involving the immune system. Things that can cause itching and/or rash include certain chemicals, ingredients in cosmetics, certain drugs, body fluids (sweat, urine), ultraviolet light, heat, cold, friction, and other things. 