Given the history that the rash persisted for longer than 3 months, the FP made the diagnosis of chronic urticaria. The cause of chronic urticaria (>6 weeks duration) is determined in less than 20% of cases. Because no cause was found in this case, the patient’s urticaria was determined to be chronic idiopathic urticaria.
Chronic urticaria is twice as common in women than in men. Urticaria is a dynamic process in which new wheals evolve as old ones resolve. The wheals result from localized capillary vasodilation, followed by transudation of protein-rich fluid into the surrounding skin. The wheals resolve when the fluid is slowly reabsorbed. Patients may benefit from avoiding potential urticarial precipitants such as aspirin, nonsteroidal anti-inflammatory drugs, opiates, and alcohol.
Second-generation H1 antihistamines, such as cetirizine, should be prescribed as first-line treatment for chronic urticaria. Increasing the dose of cetirizine from 10 mg/d to 20 mg/d produces a significant improvement in the severity of wheals and itching in urticaria refractory to the standard doses of antihistamines. The National Institute for Health and Care Excellence (NICE) notes in its 2014 evidence summary that international guidelines suggest that non-sedating antihistamines may be used at up to quadruple the manufacturers’ recommended dosages before changing to an alternative therapy. NICE recommends waiting up to 4 weeks to allow full effectiveness of the antihistamines before considering referral to a specialist.
The patient in this case was started on cetirizine 10 mg twice daily with written instructions to gradually increase up to 20 mg twice daily if the lower doses were not working. With cetirizine 20 mg twice daily, the chronic urticaria subsided and the patient was satisfied with the results.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R. Urticaria and angioedema. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013: 863-870.
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