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Can Zinc Really Stop a Cold in its Tracks?

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.

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5 Responses to “Can Zinc Really Stop a Cold in its Tracks?”

  1. Sarah Myers Says:

    This seems to be a very relevant topic as we are entering into flu and cold season, Laura. I have already noticed many more customers seeking self-care in the pharmacy aisles. Although I have never tried zinc for a cold, I occasionally hear some of my family members comment on how they need to be increasing their zinc when they start to notice the symptoms of a cold. I never knew what evidence there was to support its use for the common cold though. I find it interesting that this study suggests zinc acetate is effective in shortening the duration and lessening the symptoms of a cold however, treatment with zinc gluconate and zinc sulfate is not supported. Zinc gluconate seems to be the more commonly used form of zinc in lozenges, such as Nature’s Way and Cold-Eeze.

    Your post addressed possible short-term side effects, such as nausea and bad taste. In your research, did you find any additional adverse effects associated with long-term zinc use for prevention of colds?

  2. Brittany Santee Says:

    I agree with Sarah that this is relevant to the season right now. With many Americans now looking for more natural ways to cure sicknesses and disease, zinc lozenges have been getting a lot of attention recently. I like how you set apart the different forms of zinc, saying that the acetate is the only one showing effectiveness, while the gluconate and sulfate did. I think this is a good thing to point out because the article by Ms. Beck didn’t acknowledge any difference, and that is what the average patient is going to be thinking like. Hopefully as pharmacists, we can help patients distinguish between the different types and choose a treatment that is effective.

    One question I would ask is what is the maximum dosage? Are there negative effects if someone takes a lot more than the recommended dosing because they think it will make them get better faster?

  3. Paul Bicknell Says:

    I have never tried zinc for treatment of a cold, and I didn’t know its use was that well supported. I like how you mentioned that patients should weigh side-effects against the benefits of using zinc and can always discontinue its use if the side-effects are worse then those of the condition that it is treating, but in general zinc seems like a viable option for patients to use to help overcome colds. Pharmacist education would certainly be important in helping patients choose the zinc formulation that would be the most beneficial for them. I think the specific and practical advice you gave at the end of your post about how a patient should use zinc is very beneficial for helping a patient to know exactly what to do.

  4. Laura Cummings Says:

    Good questions! Sarah, I looked into the details of Prasad’s study and found that extended use (6-8 weeks) of zinc can cause copper deficiency. The University of Missouri also warns that long-term (undefined) use of 100mg or more of zinc daily can reduce HDL and immunity, increase prostate cancer risk, and interfere with antibiotic absorption. Given that a typical cold lasts roughly a week, this doesn’t present a significant concern to the majority of patients. However, if an individual is prone to frequent colds, it would be wise to monitor zinc consumption. Furthermore, Prasad recommended that if an individual shows no improvement in symptoms after taking zinc as directed for 3 days, an underlying problem may be present that requires further medical evaluation. Brittany, I didn’t find a specific definitive daily maximum, however, the Office of Dietary Supplements within the National Institute for Health recommends no more than 40mg of zinc daily, long-term. High doses, such as the 75mg+ lozenges mentioned above are only approved for short term use, usually around 1 week. You’re right, Paul! It’s important for us to know about the details of using zinc for colds so we can best help our patients.

  5. Calvin Anderson Says:

    Hey Laura, I liked how your blog post started, it was rather humorous. But getting back to the topic at hand, I always knew that zinc (in controlled doses) was good for you, but I did not know of its potential uses for the common cold. Because the cold is so….common, it would seem that zinc poses itself as a new treatment option that we can recommend to our patients. I for one, and I think Paul as well, would like to know how zinc works in the body to reduce cold symptoms. Does it go after the virus directly? Also, I like how you included directions towards the end of your blog post, which we could be able to use to tell our patients how to properly take zinc. I also support Sarah’s question whether or not the long-term effects of zinc have been analyzed. Again, we should make sure that our recommendations do not harm the patient!

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