OBJECTIVE: To study the potential efficacy and tolerability of a natural multiherbal formula (Immumax) containing echinacea extract 120 mg, garlic powder 100 mg, nigella sativa oil 200 mg, and Panax ginseng extract 50 mg plus Vitamin C 50 mg and elemental zinc 7.5 mg in the treatment of patients suffering from the common cold. DESIGN AND SETTING: The study was conducted in a prospective, double-blind, randomized, controlled study design in an outpatient setting. PATIENTS AND METHODS: Sixty-two eligible patients with symptoms of the common cold were randomized to either Immumax or placebo treatment groups for the duration of their symptoms or a maximum of 14 days. Resolution rates were estimated using Kaplan-Meier analysis, and resolution profiles were compared between groups using the log-rank test. The mean percentage change in total symptom severity scores at days 4 and 8 from baseline were compared between the two groups by one-way analysis of variance (ANOVA). RESULTS: The median (interquartile range) time to resolution of all symptoms was 8 (5-9) days in the placebo group and 4 (3-6) days in the Immumax group. The results of the log-rank test indicate that symptoms resolved significantly faster in the Immumax group than in the placebo group (P < 0.001). The mean percentage reduction in total symptom severity scores from baseline at days 4 and 8 was significantly greater in the Immumax group than in the placebo group by one-way ANOVA (P < 0.01). CONCLUSION: We can conclude from our study that Immumax is helpful in reducing the duration and severity of common cold symptoms.