Vitamin C has been claimed to be an effective treatment for a common cold. The common cold is infectious and an average person gets it more than one times during the year.
A Noble prize Winning chemist Linus Pauling promoted a view of Vitamin C and its impact on common cold in 1970.
Vitamin C is very commonly used for the cure of common cold and flu.
There has been numerous research done on this whether Vitamin C has any role on the common cold. Studies that have been done on Vitamin C usually show very modest to little effect from Vitamin C.
Not fully proven, but large doses of vitamin C may help to reduce the duration of common cold. Results vary person to person, some people improve while others do not. Different trials conducted on different age group persons and there was no clear indication of the relative benefits of vitamin C doses. However, in research that done after common cold symptoms occurred, there was some evidence that a large dose had greater impact and benefits than lower doses.
For vitamin C oral usage, you have to find your bowel tolerance. A large dose of vitamin C may upset your stomach and leads to diarrhea.
Vitamin C reduces the cold severity
Vitamin C reduces cold duration
Long-term daily supplementation with vitamin C in large doses does not appear to prevent colds. The relation of dose to therapeutic benefit needs further research.