Does ascorbic acid (Vitamin C) reduce the duration of the common cold?

From the Guidelines

Vitamin C may be beneficial in reducing the duration of the common cold, particularly when taken at the onset of symptoms, as suggested by the European Position Paper on Rhinosinusitis and Nasal Polyps 2020 1. The study found that while routine vitamin C supplementation is not justified for the general population, it may be useful for individuals exposed to brief periods of severe physical exercise. When considering the use of vitamin C for the common cold, it is essential to weigh the potential benefits against the low cost and safety of the supplement. Some key points to consider include:

• The consistent effect of vitamin C on the duration and severity of colds in supplementation studies 1
• The potential for individual variation in response to vitamin C therapy, making it worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them 1
• The importance of adequate rest, hydration, and other supportive measures in conjunction with vitamin C supplementation
• The potential for very high doses of vitamin C to cause digestive issues like diarrhea and stomach cramps, emphasizing the need for moderate dosing In terms of specific dosing, the study does not provide explicit recommendations, but suggests that vitamin C may be beneficial when taken at the onset of symptoms. Overall, the available evidence suggests that vitamin C may be a useful adjunctive therapy for the common cold, particularly when taken at the onset of symptoms, and its low cost and safety make it a worthwhile consideration for individual patients 1.

From the Research

Effect of Ascorbic Acid on Common Cold Duration

• The duration of common cold symptoms can be reduced by regular consumption of vitamin C, as found in a study published in the Journal of the American Academy of Nurse Practitioners 2.
• A review of 30 trials on the role of oral ascorbic acid in preventing and treating colds, published in The Cochrane database of systematic reviews, revealed a consistently beneficial but generally modest therapeutic effect on duration of cold symptoms, with a reduction of approximately half a symptom day per cold episode 3.
• A meta-analysis of 9 randomized controlled trials, published in BioMed research international, found that administration of extra therapeutic doses of vitamin C at the onset of cold, despite routine supplementation, helped reduce its duration 4.
• Another study published in Nutrients found that regularly administered vitamin C has shortened the duration of colds, indicating a biological effect, although the role of vitamin C in common cold treatment is unclear 5.
• A review of 21 placebo-controlled studies, published in the Scandinavian journal of infectious diseases, found that vitamin C reduced the duration of episodes and the severity of the symptoms of the common cold by an average of 23% 6.

Key Findings

• Regular vitamin C consumption may reduce the duration of cold symptoms in both adults and children 2, 3.
• High doses of vitamin C may produce greater benefits than lower doses in reducing the duration of cold symptoms 3, 5.
• The relation of dose to therapeutic benefit needs further exploration 3.
• Extra doses of vitamin C could benefit some patients who contract the common cold despite taking daily vitamin C supplements 4.