In a systematic review and meta-analysis, intranasal antihistamines relieved nasal symptoms in idiopathic non-allergic rhinitis-affected patients. The objective of this study was to evaluate how intranasal antihistamines affected idiopathic rhinitis (the most common type of non-allergic rhinitis).

For a relevant literature search, Medline, Embase, and Cochrane Library databases were inspected.  Non-randomized comparative parallel group trials and randomized controlled trials that compared intranasal antihistamines to other intranasal antihistamines or placebo were incorporated. The alteration in total nasal symptom score (TNSS), illness-specific quality of life questionnaire, was the major endpoint. Other reported individual symptom scores, nasal symptom scores, and adverse events were the secondary endpoints ascertained.

Overall, 6 trials were considered appropriate for inclusion out of 987 trials that evaluated 675 volunteers. Intranasal antihistamine reduced the total nasal symptom scores as compared to placebo. In one trial, symptoms that were measured on visual analogue scale (VAS) were also reduced. In terms of effectiveness, no discernable difference between intranasal antihistamines was reported. The most common side effect recorded was a bitter taste sensation. Hence, intranasal antihistamines may be valuable for the management of idiopathic non-allergic rhinitis.