A randomized trial of zinc nasal spray for the treatment of upper respiratory illness in adults

Purpose We performed a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of 0.12% zinc sulfate nasal spray for reducing the duration and severity of acute upper respiratory infections. Subjects and methods Patients with acute onset of upper respiratory illness of less than 24 hours’ duration were eligible for the study. A nasopharyngeal swab was obtained at the time of enrollment for viral culture. Participants were randomly assigned to receive either 0.12% zinc sulfate or isotonic placebo spray. The medication was administered as two inhalations in each nostril four times a day. Each patient completed a diary card twice a day to record oral temperature, symptoms, and adverse effects. Symptoms were scored as absent (0), mild (1), moderate (2), or severe (3). Results One hundred eighty-five subjects volunteered to participate, and 160 met the criteria for enrollment. The median duration of all symptoms was 7 days in both groups (P = 0.45), and the median duration of nasal symptoms was 6 days in both groups (P= 0.12). After adjustment for baseline differences in severity, patients receiving zinc had a significant reduction in the total symptom score (P= 0.02) and the nasal symptom score (P= 0.02) on day 1, but not on any of the other days. Adverse effects were mild and had no significant association with the use of zinc. A respiratory virus was identified in 9 of the 160 participants; 6 of these were rhinovirus. Conclusion A low concentration of zinc sulfate nasal spray had no effect on the duration of the common cold.