Emedastine difumarate (2 mg b.i.d.) was compared to loratadine (10 mg o.d.) in a randomized, double-blind, multicentre trial for 4 weeks in 192 patients with idiopathic chronic urticaria. After one week of treatment significant differences were recorded: body skin involvement diminished to 0-10% in 57.1% of emedastine patients vs. 38.2% of loratadine patients (p = 0.0019) and 83.3% had a total urticaria symptom score of 0-1 vs. 64.5% with loratadine (p = 0.0134). After 4 weeks of treatment the efficacy of the two drugs was similar in terms of mean change in total urticaria symptom score (- 5.57 +/- 3.15 with emedastine - 5.67 +/- 3.26 with loratadine), proportion of symptom-free patients (52.4% vs. 54.5%), intensity of erythema, number of hives, size of the largest hive, extent of skin area involved and overall assessment of urticaria symptoms.Twenty-three emedastine patients (23.9%) and 17 loratadine patients (17.7%) experienced an adverse event. Nineteen events in 15 emedastine patients and 9 in 9 loratadine patients were related to treatment (p = 0.0294). Only one event caused discontinuation in both treatment groups. The most common adverse event was sleepiness (7 patients with emedastine and 2 with loratadine). Emedastine is well tolerated, and as effective as loratadine in the short-term treatment of chronic idiopathic urticaria.