Vitamin C for the Common Cold

Common cold may be cut short by regularly taking vitamin C but not by starting it when sick

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) For years, vitamin C has been said to help people stay healthy and recover faster from a cold. Science says this may be true in some ways.

A recent review of past research showed that vitamin C did not protect against catching a cold. However, it did speed up recovery.

People who regularly took vitamin C were not less likely to catch a cold, but were more likely to recover faster. However, people who started taking vitamin C after they were already sick did not recover faster.

"Talk to your doctor about which vitamins to take."

Researchers led by Harri Hemilä, MD, PhD, of the Department of Public Health at the University of Helsinki in Finland, looked at trials using vitamin C supplements.

They used only trials that were placebo-controlled – meaning that vitamin C was compared to a sugar pill. So people in the trials either took vitamin C or they did not, and the two groups were compared to each other.

The researchers put together all the data from the trials and looked at how many people caught a cold, how long the cold lasted and how severe the cold symptoms were.

There were 29 trials involving a total of 10,708 people who regularly took vitamin C over the course of the study. So, these people were taking the supplement whether they were healthy or sick. Results of these trials showed that taking vitamin C did not lower the risk of catching a cold.

A number of trials focused on athletes. In total, 598 athletes were included in these trials. For this specific set of people, regularly taking vitamin C was linked with a lower risk of catching a cold, and their risk was about half that of the general population.

There were 31 trials that looked at the effect of regularly taking vitamin C on the duration of a cold. Regularly taking vitamin C reduced the length of cold by 8 percent in adults and 14 percent in children. So, if a cold typically lasts for five days, an adult who regularly takes vitamin C may recover about half a day sooner.

Only seven trials looked at using vitamin C as a therapy – meaning taking vitamin C after becoming sick. Vitamin C did not shorten the duration of a cold when taken as therapy.

The authors concluded that regularly taking vitamin C did not  lower the likelihood of catching a cold for most people. Regularly taking vitamin C did seem to shorten a cold, but did not appear to work as a therapy after a cold had started.

The authors wrote, “Nevertheless, given the consistent effect of vitamin C on the duration and severity of colds in the regular supplementation studies, and the low cost and safety, it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them.”

This study was published January 31 in the Cochrane Database of Systematic Reviews. Funding information and conflicts of interest were not included with the article summary.

Reviewed by: 
Review Date: 
February 14, 2013
Last Updated:
February 15, 2013