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Can Zinc Really Stop a Cold in its Tracks?

Sunday, November 10th, 2013

By Laura Cummings, PharmD Student Cedarville University

‘Tis the season for the spread of the common cold. While not always severe, the congestion, cough, and other cold symptoms are often irritating and can detract from focus and productivity, which drives many cold sufferers to seek a quick solution at the first sign of symptoms. One option that has gained popularity in recent years is zinc lozenges, but have they been scientifically proven effective?

In her article “Do some foods or supplements actually help treat a cold?” Leslie Beck explores several non-drug options commonly used in an attempt to reduce the duration and/or severity of the common cold.1 One treatment that she discusses is zinc lozenges. I agree that some zinc lozenges are scientifically supported as effective, however I disagree with her recommendation of zinc gluconate and zinc citrate lozenges specifically. Furthermore, the article does not include citations to facilitate further research by interested readers.

Although the exact mechanism of action of zinc is still under investigation, researchers have determined that it exerts its effects on the body’s cells rather than directly on the viral cells themselves. This is because the irritating symptoms associated with the common cold are due to an overreaction of the body’s immune cells. Therefore, inhibition of these cells by zinc allows the effective elimination of the virus from the body to occur, while simultaneously reducing the excessive immune effects that cause symptoms such as a runny nose, sneezing, cough, and congestion.2

Science et. al. analyzed 17 randomized controlled clinical trials testing for the treatment effects of various types and dosage forms of zinc on the common cold, when compared with placebo.3 The most commonly supported conclusion was that high-dose zinc acetate treatment was capable of shortening a cold by about two and a half days in adults. It is important to note that zinc gluconate and zinc sulfate did not show similar effectiveness, nor did any zinc treatment used in the treatment of colds in children. Although Science et. al. did not suggest the reasoning behind this, Prasad et. al. have proposed that this is due to increased bioavailability of the acetate form.4 Another suggested conclusion was that zinc was capable of reducing the severity of cold symptoms as rated by patients on graded scales. However, the studies also revealed that side effects of oral zinc can include bad taste and nausea. Another systematic review conducted by Singh helped solidify the specific recommendations for therapy.5 Through the analysis of 18 randomized controlled clinical trials, the authors were able to conclude that in order to be most effective, zinc therapy should begin within 24 hours of the onset of symptoms and should consist of lozenges containing ≥ 75mg of zinc.

So what does this mean practically? When you begin experiencing cold symptoms, stop by the OTC aisle to pick up some 75mg zinc acetate lozenges. Start taking them within 24 hours of the first symptoms and continue as directed on the box (typically every 2-3 hours while awake) until symptoms are gone. You may experience side effects of bad taste and nausea, in which case you can choose to discontinue therapy if you determine that the side effects of zinc outweigh its ability to shorten your cold. This treatment should shorten the duration of your cold by at least 2 days and may decrease the severity of the cold while it lasts.

Have you tried zinc for colds in the past? Did you find it effective?

References

  1. Beck, Leslie. Do some food or supplements actually help treat a cold? The Globe and Mail. Oct. 14, 2013. Available from http://www.theglobeandmail.com/life/health-and-fitness/ask-a-health-expert/do-some-foods-or-supplements-actually-help-treat-a-cold/article14842492/. Accessed November 2, 2013.
  2. Hendley J. The host response, not the virus, causes the symptoms of the common cold. Clinical Infectious Diseases: An Offiial Publication Of the Infections Diseases Society Of America [serial online]. April 1998;26(4):847-848. Available from MEDLINE with Full Text, Ipswich, MA. Accessed November 6, 2013.
  3. Science M, Johnstone J, Roth D, Guyatt G, Loeb M. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ: Canadian Medical Association Journal=Journal De L’association Medicale Canadienne [serial online]. July 10, 2012;184(10):E551-E561. Available from MEDLINE with Full Text, Ipswich, MA. Accessed November 2, 2013.
  4. Prasad A, Fitzgerald J, Bao B, Beck F, Chandrasekar P. Duration of symptoms and plasma cytokine levels in patients with the common cold treated with zinc acetate. A randomized, double-blind, placebo-controlled trial. Annals of Internal Medicine [serial online]. August 15, 2000;133(4):245-252. Available from MEDLINE with Full Text, Ipswich, MA. Accessed November 6, 2013.
  5. Singh M, Das R. Zinc for the common cold. Cochrane Database Of Systematic Reviews. [serial online]. June 2013;(6) Available from CINAHL Plus with Full Text, Ipswich, MA. Accessed October 19, 2013.