| Urticaria |
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| dermatology | |
Urticaria (or '''hives''') is a skin condition, commonly caused by an allergic reaction, that is characterized by raised red skin Welts . It is also known as '' Nettle rash'' or ''uredo''. Welts from hives can appear anywhere on the body, including the face, lips, tongue, throat, and ears. Welts may vary in size from about 5 mm (0.2 inches) in diameter to the size of a dinner plate; they typically Itch severely, sting, or burn, and often have a pale border. Urticaria is generally caused by direct contact with an allergenic substance, or an immune response to food or some other Allergen , but can also appear for other reasons. The rash can be triggered by quite innocent events, such as mere rubbing, or exposure to cold. PATHOPHYSIOLOGY The skin lesions of urticarial disease are caused by an inflammatory reaction in the skin, causing leakage of capillaries in the Dermis , and resulting in an Oedema which persists until the interstitial fluid is absorbed into the surrounding cells. Urticarial disease is thought to be caused by the release of Histamine and other mediators of inflammation (cytokines) from cells in the skin. This process can be the result of an allergic or non-allergic reaction, differing in the eliciting mechanism of histamine release.
Histamine and other pro-inflammatory substances are released from Mast Cells in the skin and tissues in response to the binding of Allergen -bound IgE antibodies to high affinity cell surface receptors. Basophils and other inflammatory cells are also seen to release histamine and other mediators, and are thought to play an important role, especially in chronic urticarial diseases.
Mechanisms other than allergen-antibody interactions are known to cause histamine release from mast cells. For instance, a diverse group of signaling substances called Neuropeptides have been found to be involved in emotionally induced urticaria. Dominantly inherited cutaneous and neurocutaneous porphyrias (porphyria cutanea tarda, hereditary coproporphyria, variegate porphyria and erythropoietic protoporphyria) have been associated with solar urticaria. Drug-induced solar urticaria should be investigated for porphyrias. Caused by IgG binding not IgE MISCONCEPTION
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TREATMENT & MANAGEMENT Urticarias can be very difficult to treat. Most treatment plans for urticaria involve being aware of one's triggers, but this can be difficult since there are several different forms of urticaria and people often exhibit more than one type. Also, since symptoms are often Idiopathic there might not be any clear trigger. If one's triggers can be identified then outbreaks can often be managed by limiting one's exposure to these situations. Drug treatment is typically in the form of Antihistamine s such as Diphenhydramine , Hydroxyzine , Cetirizine and other H1 Receptor antagonists. These are taken on a regular basis to protective effect, lessening or halting attacks. For some people, H2-receptor Antagonist s such as Cimetidine (Tagamet) and Ranitidine (Zantac) can also help control symptoms either protectively or by lessening symptoms when an attack occurs. When taken in combination with a H1 antagonist it has been shown to have a synergistic effect which is more effective than either treatment alone. The use of ranitidine (or other H2 antagonist) for urticaria is considered an off-label use, since these drugs are primarily used for the treatment of Peptic Ulcer disease (PUD) and Gastroesophageal Reflux disease (GERD). Tricyclic Antidepressant s such as Doxepin , also are often potent H1 and H2 antagonists and may have a role in therapy, although side effects limit their use. For very severe outbreaks, an oral Corticosteroid such as Prednisone is sometimes prescribed. However this form of treatment is controversial because of the extensive side effects common with corticosteroids and as such is not a recommended long-term treatment option. None of these treatments are surefire means of controlling attacks. Some people prove to be treatment resistant, and medications can suddenly cease being as effective as they once were. In these instances, changes to a treatment plan can sometimes help. It can be difficult to determine appropriate medications since some such as Loratadine require a day or two to build up to effective levels, and since the condition is intermittent and outbreaks typically clear up without any treatment. While the disease is obviously physiological in origin, psychological treatments such as Stress Management can sometimes lessen severity and occurrence. Additionally, methods similar to psychological pain management can be used to shift focus away from the uncomfortability and itchiness during an attack. If hives or Angioedema occur with any of the following symptoms, contact your doctor right away.
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