Outpatient management of acute urticaria: the role of prednisone.

STUDY OBJECTIVE: To evaluate the efficacy of a 4-day "burst" course of prednisone added to standard treatment with H1 antihistamines for the management of acute urticaria in outpatients.

DESIGN: Prospective, randomized, double-blinded, clinical trial.

SETTING: Emergency department of an urban tertiary care teaching hospital.

PARTICIPANTS: Adult patients with urticarial rash of no more than 24 hours' duration, regardless of cause. Patients were excluded if they manifested wheezing, stridor, or angioedema or if they had taken antihistamines or glucocorticoids within 5 days of arrival at the ED. Patients also were excluded if there was a history of diabetes or active peptic ulcer disease.

INTERVENTIONS: All patients were asked to evaluate the severity of pruritus ("itch score") on a 10-cm visual analog scale. Patients were then given diphenhydramine, 50 mg intramuscularly, and discharged home on a regimen of hydroxyzine, 25 mg orally, every 4 to 8 hours for pruritus, plus either prednisone, 20 mg, or placebo orally every 12 hours for 4 days. Patients' conditions were reassessed clinically, with itch score calculated again 2 days later, and again at 5 days by telephone.

RESULTS: Forty-three patients were enrolled; 24 received prednisone and 19 received placebo. The two groups had similar itch scores at enrollment (prednisone, 8.1 +/- 1.7; placebo, 7.4 +/- 2.1, P = .25 [ANOVA]), but at 2- and 5-day follow-up the prednisone group had significantly lower itch scores (1.3 +/- 1.3 and .0 +/- .0 versus 4.4 +/- 2.2 and 1.6 +/- 1.0, respectively; P < .0001 [ANCOVA] at each interval) and greater clinical improvement in rash. Response did not correlate with age, sex, or identification of an allergen. No adverse effects were noted in either group.

CONCLUSION: The addition of a prednisone burst improves the symptomatic and clinical response of acute urticaria to antihistamines. Patients' conditions improved more quickly and more completely when prednisone was administered, without any apparent adverse effects.