First-Generation OTC Antihistamine Use and Voice Function in Individuals with Allergic Rhinitis: A Preliminary Report of Clinically Impactful Findings.

Purpose: The primary goal of this investigation was to characterize the effect of the first-generation, over-the-counter antihistamine Chlor-Trimeton on laryngeal structure and function in a previously unstudied population - individuals diagnosed with allergic rhinitis who routinely take over-the-counter antihistamines and deny the experience or diagnosis of voice disorder.

Study Design: Prospective within-participant multimodality repeated measures design.

Methods: Eight consented participants (seven females, one male) previously diagnosed with allergic rhinitis and without history of voice disorder who routinely took over-the-counter antihistamines completed the study. Volunteers completed the following measures before and 2hours after antihistamine administration: perceptual vocal function measures, phonation threshold pressure (PTP), acoustic measures, and laryngeal imaging. All pre- and post-administration data were descriptively analyzed for clinically significant change.

Results: No clinically significant differences were identified for any acoustic or aerodynamic measures taken. Analyses of laryngeal imaging data indicated that all participants had evidence of mucosal changes in one or more of the following parameters: increased vascularity, mucus in the anterior commissure, and vocal fold color changes, all of which are consistent with prior descriptions of allergy larynx.

Conclusions: Empirical study of laryngeal appearance in individuals diagnosed with allergic rhinitis, affirmed clinical observations of laryngeal tissue changes consistent with allergy larynx. Stable PTP suggests potential vocal fold cover adaptations from routine use of over-the-counter antihistamines that may buffer the typical desiccating effect on voice function observed in prior studies of healthy individuals.