A cochrane review suggested that taking zinc within onset of cold symptoms is effective at lingering the common cold.

What's the optimal dosage?

1 Answer 1


As the study says:

Zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms in healthy people but some caution is needed due to the heterogeneity of the data. As the zinc lozenges formulation has been widely studied and there is a significant reduction in the duration of cold at a dose of ≥ 75 mg/day

Examine.com states;

Superloading zinc by taking up to 100mg zinc a day is confirmed to be safe in the short term (2-4 months), but because this dose is higher than the 40mg Tolerable Upper Limit (TUL) of zinc, prolonged superloading is not advised.

However, as can be seen in the PubMed comments here there are significant criticisms of the summary made. This lead to the withdrawal of the publication in 2015

Zinc Supplementation Decreases Incidence Of Infections In The Elderly: Effect Of Zinc On Generation Of Cytokines And Oxidative Stress found:

Supplementation of 45mg elemental zinc for a period of 12 months in elderly persons who had low baseline zinc levels, the infection rate seen with supplementation (29%) was lower than placebo (88%) although upper respiratory tract infection rates trended to be less common (50% reduction) but this failed to reach significance.

In summary:

The 2013 Cochrane study was trashed by one reviewer and got taken down. There is no significant evidence that it reduces the common cold symptoms in adults if taken as one is starting.

  • Where do you get "one study"? I linked to a review. Why do you think that what happens to be a good daily dose is equivalent to what happens to be a good one time dose?
    – Christian
    Jul 20, 2016 at 14:35
  • @Christian, you are correct, it appears to be a review of trials. I did a bit more digging and updated my answer.
    – John
    Jul 20, 2016 at 15:34
  • The 45mg number is a number for a daily dosage. Why do you think it's relevant for taking zinc as a one-time intervention? Especially given that the studies that show a useful effect from a one time intervention use ≥ 75mg?
    – Christian
    Jul 20, 2016 at 16:56
  • No, 15mg is reccomended daily dosage. Evidently you don't agree with my answer and have made your own assumptions about what the 'correct' answer to your question should be.
    – John
    Jul 20, 2016 at 16:58
  • 1
    Final comment: you assumed from a invalid review that zinc significantly helps the common cold symptoms.
    – John
    Jul 20, 2016 at 17:22

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