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Duration of Symptoms and Plasma Cytokine Levels in Patients with the Common Cold Treated with Zinc Acetate: A Randomized, Double-Blind, Placebo-Controlled Trial

Ananda S. Prasad, MD, PhD; James T. Fitzgerald, PhD; Bin Bao, MD, PhD; Frances W.J. Beck, PhD; and Pranatharthi H. Chandrasekar, MD
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Copyright ©2004 by the American College of Physicians

Ann Intern Med. 2000;133(4):245-252. doi:10.7326/0003-4819-133-4-200008150-00006
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Background: Adults and children in the United States get two to six colds per year. Evidence that zinc is effective therapy for colds is inconsistent.

Objective: To test the efficacy of zinc acetate lozenges in reducing the duration 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 acetate or placebo every 2 to 3 hours while awake as long as they had cold symptoms.

Measurements: Subjective symptom scores for sore throat, nasal discharge, nasal congestion, sneezing, cough, scratchy throat, hoarseness, muscle ache, fever, and headache were recorded daily for 12 days. Plasma zinc and proinflammatory cytokine levels were measured on day 1 and after participants were 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 group 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 discharge (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 × time interaction). Mean changes in soluble interleukin-1 receptor antagonist level differed nonsignificantly between the zinc group and the placebo group (difference between changes, −89.4 pg/mL [CI, −243.6 to −64.8 pg/mL]).

Conclusion: Administration of zinc lozenges was associated with reduced duration and severity of cold symptoms, especially cough. Improvement in clinical symptoms with zinc treatment may be related to a decrease in proinflammatory cytokine levels; however, in this study, the observed differences between changes in cytokine levels in zinc and placebo recipients were not significant.


Grahic Jump Location
Figure 1.
Duration of cold symptoms in the zinc group (squares) and the placebo group (circles).

Fifty percent of the zinc recipients were well in 3.8 days, and 50% of the placebo recipients were well in 7.7 days.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Changes in severity scores after treatment in the zinc group (squares) and the placebo group (circles).P

Values are given as the mean ± SE. Repeated-measures analysis indicated a significant effect for treatment × time between the zinc and placebo groups over the 12 days of the study ( = 0.002).

Grahic Jump Location




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Summary for Patients

Zinc Acetate Lozenges To Treat the Common Cold

Copyright ©2004 by the American College of Physicians


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