Objective: To investigate dose-related effects of ephedrine on olfactory function in healthy subjects.Design: Placebo-controlled, randomized, double-blind study.Methods: Drug effects were assessed using olfactory and trigeminal psychophysical measures (intensity ratings, odor discrimination, butanol and formic acid thresholds); nasal patency was assessed by means of anterior rhinoresistometry. The investigation was performed in 24 healthy volunteers; subjects were assigned to treatments A, B, or C (3 groups with 8 subjects each; 4 women and 4 men per group). All subjects received either placebo or ephedrine in both nostrils; group A subjects received placebo, and group B and C subjects received ephedrine in dosages of 0.12 and 0.24 mg, respectively.Results: Treatment with ephedrine produced a tendency toward an increase of nasal airflow. However, during the time of observation there was no significant difference between effects produced by the 2 dosages. Ephedrine had no systematic effect on measures of olfactory function. The only significant correlation to the nasal airflow was found for perceived intensity of the trigeminal stimuli, which increased with increasing flow.Conclusions: Ephedrine appeared to have neither negative nor major positive effects on intranasal chemosensory function in healthy subjects. This indicates that ephedrine may be used as a decongestant in studies on olfaction.