Zinc and the common cold: a meta-analysis revisited

Area of Science:

• Pharmacology and Therapeutics
• Infectious Diseases
• Evidence-Based Medicine

Background:

• The common cold incurs substantial economic costs in the United States, exceeding $3.5 billion annually.
• Previous randomized clinical trials on zinc gluconate for common cold treatment have yielded conflicting results, creating uncertainty regarding its efficacy.

Purpose of the Study:

• To conduct a meta-analysis of published randomized clinical trials to evaluate the effectiveness of zinc gluconate lozenges in treating the common cold.
• To synthesize existing evidence to resolve conflicting findings on zinc gluconate's impact on cold symptom duration and severity.

Main Methods:

• A systematic meta-analysis was performed on randomized clinical trials investigating zinc gluconate lozenges for common cold treatment.
• The random effects model (DerSimonian and Laird) was employed for data synthesis.
• Eight relevant clinical trials were included after excluding studies using nasal rhinovirus inoculum.

Main Results:

• The meta-analysis summarized data from eight randomized clinical trials.
• The summary odds ratio for the presence of any cold symptoms at 7 days was 0.52 (95% confidence interval: 0.25-1.2).
• The confidence interval includes 1, indicating a lack of statistically significant effect.

Conclusions:

• Despite numerous randomized trials, current evidence does not support the effectiveness of zinc gluconate lozenges in reducing the duration of common colds.
• Further high-quality research may be needed, but existing data suggest limited therapeutic benefit.