Figure 1.

Study design. The study consisted of two separate double-blind phases. Phase one was an in-hospital assessment of the effectiveness and tolerability of levocetirizine and hydroxyzine at two doses. Phase two was a comparison of levocetirizine monotherapy vs. levocetirizine plus hydroxyzine at night. Complete data were collected at baseline and at the end of each study period. Broken lines indicate collection of urticaria activity scores during the assessment period.