Taking vitamin C prevents the common cold
Regular vitamin C does not prevent colds in the general population. It shortens episodes by roughly 8% in adults — a matter of hours, not days.
AI review of the sources below, no human approval · Reviewed
This verdict was generated by AI from the papers listed on this page and published without human sign-off. AI can misread or miss studies — check the sources yourself. Not medical advice.
What the research says
Cochrane's review of 29 trials with over 11,000 participants found no reduction in cold incidence for people taking ≥200 mg/day regularly. Duration was shortened by about 8% in adults and 14% in children. The one exception is people under short bursts of extreme physical stress — marathon runners, skiers, soldiers in subarctic conditions — where incidence roughly halved. Starting vitamin C after symptoms begin has shown no consistent benefit.
Caveats
- Exception: extreme, short-term physical stress showed a real preventive effect.
- Very high doses can cause gastrointestinal upset and raise kidney-stone risk in susceptible people.
Evidence
- Systematic reviewCochrane Database of Systematic Reviews·2013
Vitamin C for preventing and treating the common cold
No reduction in cold incidence in the general population; small reduction in duration.
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This page summarises published research for general information. It is not medical advice — talk to a clinician about your own situation.