Management of urticaria

Abstract

Urticaria is predominantly due to release of mast cell mediators, mainly histamine. Chronic idiopathic urticaria, in which disease activity continues on most days for more than 6 weeks and there is no evidence of a physical urticaria or urticarial vasculitis, is common. An external cause is rarely identified even if a thorough history and appropriate investigation based on this are undertaken. However, approximately 50% of patients with chronic idiopathic urticaria (CIU) have a serum histamine releasing factor present. In one-third of patients with CIU this is an IgG autoantibody directed against the high affinity IgE receptor (FceRI) or less frequently against IgE. Patients with autoinimune urticaria, are clinically more severe. Urticaria can affect the quality of life markedly, being comparable to that of patients awaiting triple coronary by-pass surgery. The rational management of urticaria takes account of likely causes and mediators involved. However explanation and attention to general measures such as minimizing stress, overheating and alcohol are important. Aspirin, nonsteroidal anti-inflammatory drugs and opiates should be avoided if possible. Exclusion diets such as of food colourings and additives may be of some value to a limited number of patients. Second- and third-generation low sedation H1 antagonists are the treatment of choice and improve many patients. Addition of an H2 antagonist or a mast cell stabilizing drug may provide additional benefit for a few. There are reports that leukotriene receptor antagonists improve some patients. Oral steroids are reserved if possible for severe exacerbation of chronic urticaria, and disabling pressure urticaria. Third-line therapies involving immunosuppressive agents are only appropriate for patients with chronic urticaria refractory to other measures, and usually autoimmune. The encouraging results using short courses of oral cyclosporin, high dose intravenous immunoglobulin and plasmapheresis need to be confirmed in placebo-controlled trials, in patients with or without demonstrable serum histamine releasing activity.