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Centre for Evidence-
Based Medicine

Cold symptoms: Zinc lozenges did not reduce cold symptoms in children and adolescents

Clinical Bottom Line

Zinc gluconate lozenges were not effective for reducing symptoms of the common cold in children and adolescents.


Macknin ML, Piedmonte M, Calendine C, Janosky J, Wald, E. Zinc gluconate lozenges for treating the common cold in children. A randomized controlled trial. JAMA 1998;279:1962-7

Clinical Question

In school age children with colds, are zinc lozenges safe and effective for relief of cold symptoms?

Search Terms

Medline (using PubMed) with the search terms zinc AND cold* AND child* AND randomized controlled trial.

The Study

  • Double-blinded concealed randomised controlled trial with intention-to-treat.
  • Students in Grades 1 to 12 (median age 13 y) who had at least 2 of the following symptoms within the previous 24 hours: cough, headache, hoarseness, muscle ache, nasal congestion, nasal drainage, scratchy throat, sore throat, or sneezing.
  • Control group (n=125): 3.75 g hard candy lozenges containing sucrose, corn syrup, aminoacetic acid, cherry flavouring oils and placebo (calcium lactate pentahydrate). All students took 3 lozenges each school day; students in grades 1-6 took 2 lozenges each night, and 5 each day on the weekend; students in grades 7 - 12 took 3 lozenges each school night and 6 each day on the weekend. Students were given enough lozenges for 21 days of treatment and instructed to take the lozenges until their cold symptoms completely resolved for 6 hours.
  • Experimental group(n=124): Same as for control regimen except that lozenges contained zinc gluconate trichydrate, 10 mg instead of placebo.

The Evidence

Outcome Time to Outcome RRR 95% CI ARR 95% CI NNT 95% CI
School absences (number of children) N/A 10% -38% to 57% 0.020 -0.080 to 0.120 50 NNH = 13 to INF;
NNT = 8 to INF
At least 1 adverse effect Resolution of symptoms -12% (RRI) -23% to 0% -0.092 (ARI) -0.182 to -0.002 -11 (so an NNH of 11) -441 to -6


Other outcomes - Time to resolution of cold symptoms was 9 days in both groups

Appraised By

Susan Marks, BA, BEd.
Research Associate
Health Information Research Unit
McMaster University, Hamilton, Ontario, Canada.
Fax: (905) 546-0401
Email: sumarks@fhs.mcmaster.ca
Appraised February 1999.

Expiry Date