Vitamin C for Runny Nose

Regular vitamin C does not prevent colds in the general population and shortens symptoms by less than a day. Starting it after symptoms begin does nothing.

Overview

Regular vitamin C does not prevent colds in the general population and shortens symptoms by less than a day. Starting it after symptoms begin does nothing.

Verdict

Not supported

One of the best-studied supplements in medicine, and the answer is consistently no for the average person.

How It Works

Vitamin C is an antioxidant that accumulates in neutrophils and supports phagocytic function, which is the theoretical basis for the claim — a mechanism that has not translated into clinical benefit.

Dosing & Protocol

Typical dose

Recommended dose: 0.2-1g daily if used at all; no benefit once symptoms start
Expected timeframe: Any effect is on duration of subsequent colds, not the current one.

Protocol

form: Ascorbic acid
notes: No benefit when started after symptom onset
duration: Continuous — not as-needed
starting dose: 200mg-1g daily if used

Evidence

What the studies say

The Cochrane review of over 29 trials and 11,000 participants found no reduction in cold incidence with regular supplementation in the general population. Duration was shortened by about 8% in adults, roughly half a day across a typical cold. Therapeutic dosing started after symptom onset showed no consistent effect on duration or severity. A separate subgroup of people under extreme physical stress — marathon runners, soldiers in subarctic conditions — did show roughly halved incidence, which does not generalise.

Vitamin C for preventing and treating the common cold

Score: 9/10

2013

systematic_review

n=11306

Hemila H, Chalker E

Regular vitamin C did not reduce cold incidence in the general population but shortened duration modestly

View source

Safety

Caveats

Doses above 2g daily cause osmotic diarrhoea and increase oxalate excretion, relevant in kidney stone formers.

Less likely to help if

Almost everyone; the general population shows no incidence benefit.

Medical Disclaimer

The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.