Allergy and the skin. I—Urticaria

• Published in: BMJ 1998-04, Vol.316 (7138), p.1147-1147
• Main Authors: Greaves, Malcolm W, Sabroe, Ruth A
• Format: Article
• Language: English
• Subjects: Additives; Allergies; Antibiotics; Blood products; Clinical Review; Drugs; Food additives; Patients; Skin; Steroids; Studies
• ISSN: 0959-8138; 1468-5833
• DOI: 10.1136/bmj.316.7138.1147

Features suggestive of urticarial vasculitis Clinical Duration of weals >24 hours Weals painful rather than itchy Residual purpura, bruising, or pigmentary change Prominent systemic features (eg, fever, nephritis, arthralgia) Poor response to antihistamines Laboratory High erythrocyte sedimentation rate and raised concentrations of acute phase proteins Histopathology Venular endothelial cell swelling and disruption Leucocyte invasion of venular endothelium Extravasation of red cells Leucocytoclasia (neutrophil nuclear dust) Fibrin deposition Pathogenesis The weals in chronic urticaria are caused by a local increase in cutaneous vascular permeability, mainly in the postcapillary venules. Challenge testing should be blind challenge by numbered capsules containing the food additives suspected of being implicated (details from authors on request).\n Treatment of chronic idiopathic urticaria Avoidance of precipitating or exacerbating factors Food additives, alcohol, hot environment, stress Aspirin and non-steroidal anti-inflammatory drugs, codeine and morphine Angiotensin converting enzyme inhibitors if there is angio-oedema Topical treatments Tepid shower 1% menthol in aqueous cream 2% ephedrine spray for oral angio-oedema H1 antihistamines (with or without H2 antihistamines) or doxepin Short reducing course of prednisolone Specialist treatments Cyclosporin A Intravenous immunoglobulins Plasmapheresis Treatment with 1% menthol in aqueous cream has been proved to suppress histamine induced itching, and many patients find it helpful.