While the common cold is typically presented as a single disease, it is actually a group of diseases. Conventionally, it is used to name a mild upper respiratory illness, which can be caused by several types of viruses. The most common ones are rhinoviruses (30-50%) and coronaviruses (10-15%). Following rhinovirus infections, symptoms can appear within 10 hours and the disease is self-limited, which means that symptoms usually last up to 10 days. Common symptoms include a sore throat, stuffy nose, sneezing, and coughing. Fever is mainly observed among kids but can also appear in infected adults [1].

As there are hundreds of viruses that can cause the common cold, effective prevention in the form of vaccination currently does not exist [4]. For the same reason, there is no effective cure either. As the disease is self-limited anyway, all the available therapies are focused on easing the symptoms and shortening the duration [5]. In this context, it is a common belief that vitamin C can do both – prevent and cure a common cold.

Vitamin C is an essential part of our diets as its severe deficiency can lead to a life-threatening disease called scurvy (you can read a bit more on how Vitamin C influences our health in this article) [6]. As the human body doesn’t produce vitamin C it is important to include it in our diet. The current minimal recommended dose of vitamin C in the USA and Canada is 75 and 90 mg per day for women and men, respectively. Consumption of 5 various vegetables and fruits provides 200 to 250 mg of vitamin C [7].

The idea of using vitamin C to prevent and treat the common cold was vastly popularized by the Nobel prize winner Linus Pauling. In his book, he advocates taking up to 3000 mg of vitamin C daily (check our previous article on how a dose makes a difference), based on a test conducted on schoolchildren during a skiing camp [8]. Since then, many trials have been performed to test these claims, with various outcomes. Results from trials were gathered and analyzed to extract the conclusions. Consequently, it was shown that daily supplementation of vitamin C between 200 mg and 3000 mg had no effect on the participants’ amount of common cold incidents when compared with the placebo group. Nevertheless, it was shown that the duration was decreased by 8% and 14% for adults and children, respectively. This means that, considering 10 days as the average duration of the symptoms, for adults it would be 9.2 days and for children – 8.6 days. However, these results were not confirmed in all of the studies. Furthermore, severity was not influenced. In the case of using vitamin C as a therapeutic drug patients have been treated daily with up to 8000 mg of Vitamin C after symptoms already appeared. However, there was no difference in duration and severity between controlled and placebo groups [9–11].

In conclusion, vitamin C is an essential part of our daily diet. However, supplementation with vitamin C does not prevent infections with the common cold. Moreover, it is not effective against the disease.