Levocetirizine is effective for symptom relief including nasal congestion in adolescent and adult (PAR) sensitized to house dust mites

Background: Antihistamines are the most commonly prescribed class of medication for perennial allergic rhinitis (PAR). The primary objective of this study was to determine whether levocetirizine (Xyzal®), the active enantiomer of cetirizine, could achieve at least a 50% improvement in PAR symptoms compared to the placebo over the first week of treatment. Methods: A total of 294 patients with PAR due to house dust mites were randomized in this 8‐week double‐blind, placebo‐controlled, multicentre trial to receive either levocetirizine 5 mg/day or placebo. Mean Total Four‐Symptom Scores (T4SS) (nasal pruritus, ocular pruritus, rhinorrhoea and sneezing) were compared between treatment groups over weeks 1, 4 and 6. All individual symptom scores, including nasal congestion, were also studied. Results: Levocetirizine showed an 86% improvement in T4SS over the first week of treatment and a 47% improvement over the entire treatment period compared with placebo. Absolute changes from baseline were 3.64 and 2.47 for levocetirizine and placebo, respectively. Individual symptom scores showed statistically significant (P ≤ 0.01) differences in favour of levocetirizine for all study time‐points. Nasal congestion was unexpectedly significantly improved (P