This report of a randomized, double-masked, placebo-controlled clinical study demonstrates the effectiveness of zinc acetate lozenges on common cold symptoms in allergy-tested subjects. Subjects in the zinc and placebo groups were evenly matched with respect to sex, race/ethuicity, allergy test status, and age. Overall symptom duration waz significantly less in the zinc group than in the placebo group (mean, 3.8 days vs 6.1 days). The mean severity rating for all symptoms was lower in the zinc group than in the placebo group; this difference, however, was not statistically significant. Allergypositive subjects who used zinc had a statistically significant shorter duration of nasal symptoms than allergy-negative subjects (3.5 days vs 7.6 days). In conclusion, we propose that zinc acetate lozenges may significantly shorten the duration of common cold symptoms and relieve symptoms associated with allergies.

Background.A previous meta-analysis of 3 zinc acetate lozenge trials estimated that colds were on average 40% shorter for the zinc groups. However, the duration of colds is a time outcome, and survival analysis may be a more informative approach. The objective of this individual patient data (IPD) meta-analysis was to estimate the effect of zinc acetate lozenges on the rate of recovery from colds.Methods.We analyzed IPD for 3 randomized placebo-controlled trials in which 80–92 mg/day of elemental zinc were administered as zinc acetate lozenges to 199 common cold patients. We used mixed-effects Cox regression to estimate the effect of zinc.Results.Patients administered zinc lozenges recovered faster by rate ratio 3.1 (95% confidence interval, 2.1–4.7). The effect was not modified by age, sex, race, allergy, smoking, or baseline common cold severity. On the 5th day, 70% of the zinc patients had recovered compared with 27% of the placebo patients. Accordingly, 2.6 times more patients were cured in the zinc group. The difference also corresponds to the number needed to treat of 2.3 on the 5th day. None of the studies observed serious adverse effects of zinc.Conclusions.The 3-fold increase in the rate of recovery from the common cold is a clinically important effect. The optimal formulation of zinc lozenges and an ideal frequency of their administration should be examined. Given the evidence of efficacy, common cold patients may be instructed to try zinc acetate lozenges within 24 hours of onset of symptoms.

AIMSThe aim of this study was to determine whether the allergy status and other characteristics of common cold patients modify the effects of zinc acetate lozenges. METHODSWe had available individual patient data for three randomized placebo-controlled trials in which zinc acetate lozenges were administered to common cold patients. We used both one stage and two stage meta-analysis to estimate the effects of zinc lozenges. RESULTSThe total number of common cold patients was 199, the majority being females. Eighty percent of them fell into the age range 20-50 years. One third of the patients had allergies. The one stage meta-analysis gave an overall estimate of 2.73 days (95% CI 1.8, 3.3 days) shorter colds by zinc acetate lozenge usage. The two stage meta-analysis gave an estimate of 2.94 days (95% CI 2.1, 3.8 days) reduction in common cold duration. These estimates are to be compared with the 7 day average duration of colds in the three trials. The effect of zinc lozenges was not modified by allergy status, smoking, baseline severity of the common cold, age, gender or ethnic group. CONCLUSIONSince the effects of zinc acetate lozenges were consistent between the compared subgroups, the overall estimates for effect seemed applicable over a wide range of common cold patients. While the optimal composition of zinc lozenges and the best frequency of their administration should be further investigated, given the current evidence of efficacy, common cold patients may be encouraged to try zinc lozenges for treating their colds. British Journal of Clinical Pharmacology WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Randomized trials have shown that zinc acetate lozenges shorten the duration of common cold episodes.• One study found that the effect of zinc acetate lozenges was greater for patients with allergies. WHAT THIS STUDY ADDS• The effect of zinc acetate lozenges is not modified by allergy, smoking, baseline common cold severity, age, gender or ethnic group.• The mean effect of 3 day reduction in common cold duration with zinc acetate lozenges is clinically relevant and appears widely applicable.