Duration of symptoms and plasma cytokine levels in patients with the common cold treated with zinc acetate - A randomized, double-blind, placebo-controlled trial

Background: Adults and children in the United States get two to six colds p er year. Evidence that zinc is effective therapy for colds is inconsistent. Objective: To test the efficacy of zinc acetate lozenges in reducing the du ration of symptoms of the common cold. Design: Randomized, double-blind, placebo-controlled trial. Setting: Detroit Medical Center, Detroit, Michigan. Patients: 50 ambulatory volunteers recruited within 24 hours of developing symptoms of the common cold. Intervention: Participants took one lozenge containing 12.8 mg of zinc acet ate or placebo every 2 to 3 hours while awake as long as they had cold symp toms. Measurements: Subjective symptom scores for sore throat, nasal discharge, n asal congestion, sneezing, cough, scratchy throat, hoarseness, muscle ache, fever, and headache were recorded daily for 12 days. Plasma zinc and proin flammatory cytokine levels were measured on day 1 and after participants we re well. Results: Forty-eight participants completed the study (25 in the zinc group and 23 in the placebo group). Compared with the placebo group, the zinc gr oup had shorter mean overall duration of cold symptoms (4.5 vs. 8.1 days), cough (3.1 [95% CI, 2.1 to 4.1] vs. 6.3 [CI, 4.9 to 7.7] days), and nasal d ischarge (4.1 [CI, 3.3 to 4.9] vs. 5.8 [CI, 4.3 to 7.3] days) and decreased total severity scores for all symptoms (P < 0.002, test for treatment x ti me interaction). Mean changes in soluble interleukin-1 receptor antagonist level differed nonsignificantly between the zinc group and the placebo grou p (difference between changes, -89.4 pg/mL [CI, -243.6 to -64.8 pg/mL]). Conclusion: Administration of zinc lozenges was associated with reduced dur ation and severity of cold symptoms, especially cough. Improvement in clini cal symptoms with zinc treatment may be related to a decrease in proinflamm atory cytokine levels; however, in this study, the observed differences bet ween changes in cytokine levels in zinc and placebo recipients were not sig nificant.