FDA (Food and Drug Administration) regulators are scolding Procter and Gamble for adding Vitamin C to its Vicks cold formulas, a combination not allowed by federal regulations; the FDA issued a warning to the consumer products company, stating medications such as Vicks Nyquil and Dayquil have not been approved to contain Vitamin C. Though Procter and Gamble claims Vitamin C can help to “blunt” the effects of a cold, an FDA expert panel found that Vitamin C is not explicitly effective for the prevention or treatment of the common cold. The FDA is tasked with verifying marketing claims about drugs.
Anecdotally, a lot of people swear by Vitamin C for cold prevention. Studies do not seem to support that, however. I would be interested to know how many people believe that Vitamin C has prevented them from getting a cold, or prevented the cold from getting worse.