ASIAN PACIFIC JOURNAL OF ALLERGY AND IMMUNOLOGY (2009) 27: SUMMARY The oral administration of fexofenadine 120 mg daily is a common treatment of seasonal allergic rhi- nitis (SAR). It reduces the H1 receptor-mediated symptoms, such as sneezing, pruritus, and nasal secretion as well as non-nasal symptoms such as conjunctivitis. The objective was to assess the effect of fexofenadine on nasal symptoms (such as nasal obstruction) in seasonal allergic rhinitis. A placebo-controlled, double-blind, randomized, cross-over study was performed which yielded evidence that two-week therapy with fexofenadine 120 mg daily in patients with SAR also relieves nasal obstruction and congestion. The parameters of nasal obstruction were eva- luated by means of rhinoscopy, a subjective symptom score, and active anterior rhinomanometry. The subjective evaluation of nasal obstruction/congestion as recorded by the patient every 15 minutes for 4.5 hours after nasal al- lergen provocation showed a significant difference of the AUC (p = 0.025) between fexofenadine and placebo with a 12.8 % lower obstruction after fexofenadine. The swelling of the nasal mucosa, which was assessed by rhinosco- py for 4.5 hours after nasal allergen provocation, was 21% lower after treatment with fexofenadine ( p = 0.041). In this double-blind, placebo-controlled trial, subjective patient ratings as well as objective investigator assessments demonstrate the anti-obstructive effect of fexofenadine in nasal allergen challenge. From the Institute of Medical Statistics, Informatics and Epidemiology, University Hospital Cologne, Germany; 2 ENT Private Practice Steppenbergallee, Aachen, Germany, 3 Univer- sity Hospital of Cologne, Department of Otorhinolaryngology, Head and Neck Surgery, Cologne, Germany. Correspondence: Ralph Mösges E-mail: Ralph@Moesges.de Assessment of the Antiobstructive Effect of Fexofenadine on Nasal Allergy Chal- lenge in Patients with Seasonal Allergic Rhinitis Ralph Mösges 1 , Walter Lehmacher 1 , Norbert Pasch 2 and Julia Vent 3 Seasonal allergic rhinitis (SAR) causes H 1 receptor-mediated symptoms such as sneezing, pruri- tus, nasal secretion, and conjunctivitis. These symp- toms represent the early phase of the allergic reac- tion; its primary mediator is histamine. 1 These symp- toms are treated by oral administration of antihista- mines such as fexofenadine. 2,3 Nasal obstruction and congestion are other severe symptoms of SAR, leading to a markedly re- duced quality of life. These symptoms occur predo- minantly during the late phase of the allergic reaction and are primarily caused by a vascular mechanism which is mediated by leukotrienes, prostaglandins and kinins, in particular LTC4, LTD4, PGD2, and IL-4. 4,5 In the past, nasal obstruction was primarily treated by topically administered vasoconstrictors or glucocorticosteroids. 6-11 Recent studies show, how- ever, that histamine is involved in the pathogenesis of the late-phase reaction as well and that some anti-