Zinc acetate lozenges may reduce the duration of the common cold by nearly 3 days, according to a recent analysis published in the British Journal of Clinical Pharmacology.

Among 199 patients with the common cold who participated in three randomized placebo-controlled trials, the effect of zinc lozenges was not modified by allergy status, smoking, symptom severity, age, sex or ethnic group.

“One study indicated that zinc lozenges might be more effective for common cold patients with allergies, but we showed that the efficacy is the same for those with and without allergies. Common cold patients should be encouraged to try zinc acetate lozenges not exceeding 100 mg of elemental zinc per day for treating their colds,” said Dr. Harri Hemila, lead author of the analysis.

The 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.

Researchers had available individual patient data for three randomized placebo-controlled trials in which zinc acetate lozenges were administered to common cold patients. They used both one-stage and two-stage meta-analysis to estimate the effects of zinc lozenges.

The 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 to 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 to 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, sex, or ethnic group.

Since the effects of zinc acetate lozenges were consistent between the compared subgroups, the overall estimates for effect seem applicable over a wide range of common cold patients, according to researchers. 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, the concluded.