Vitamin C for preventing and treating the common cold.

Study answer

What this study found

Routine vitamin C prophylaxis did not reduce common cold incidence in the general community, but it did in people under brief severe physical stress. In general community trials, the pooled risk ratio for developing a cold was 0.97 (95% CI 0.94 to 1.00), whereas five heavy-exercise trials showed a risk ratio of 0.48 (95% CI 0.35 to 0.64). Prophylaxis modestly shortened cold duration, by 8% in adults and 13% in children, and reduced severity. Therapeutic vitamin C started after symptom onset showed no consistent benefit for duration or severity. Reported adverse effects were uncommon and…

Study & population

Systematic review and meta-analysis of randomized comparisons of oral vitamin C for prevention or treatment of the common cold.

Intervention

Oral vitamin C was evaluated as continuous prophylaxis and, in some trials, as treatment started after cold onset.

Key limitation

The evidence was heterogeneous across populations, doses, and outcome definitions, with many older trials and several small studies.

View full study detailsView sourceOpen PDF

Original abstract