To evaluate the efficacy and safety of clemastine fumarate injection for the treatment of acute urticaria.

A multicenter, double-blind, randomized, parallel-group, controlled study was conducted. Totally, 144 patients with acute urticaria were randomly and equally divided into 2 groups: test group treated with intramuscular injection of clemastine fumarate 2 mg every 12 hours for 24 hours, control group treated with intramuscular injection of chlorphenamine maleate 10 mg every 12 hours for 24 hours. Patients were evaluated for symptom and sign scores before, and at 0.5, 1, 2, 4, 12 and 24 hours after the start of treatment. The total response rate as well as improvement rates and partial remission (≥ 90%) rates for each symptom and sign were calculated at the above time points. Adverse reactions were recorded. Statistical analysis was carried out by a noninferiority trial, Wilcoxon rank sum test, chi-square test, analysis of variance, and a nonparameter test with SAS software.

A total of 144 patients were enrolled into this study and 138 patients completed it. There was no significant difference in the response rate between the test group and control group (78.87% (56/71) vs. 77.61% (52/67), χ²=0.02, P> 0.05). No significant difference was observed between the two groups in improvement rates for itch or size, number and edema degree of wheals at 1 hour after the initial injection (all P> 0.05), or in partial remission rates for any symptom or sign, at any of the time points (all P > 0.05). Common adverse reactions included dry mouth, headache, dizziness, etc. The incidence of lethargy was significantly lower in the test group than in the control group (11.11% (8/72) vs. 20.14% (15/72), χ²=4.451, P < 0.05).

Clemastine fumarate injection is effective for the treatment of acute urticaria, with lower incidence of lethargy compared with chlorphenamine maleate injection.

Urticaria; Clemastine; Chlorpheniramine; Randomized controlled trial; Treatment outcomes