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Zinc and the Common Cold

By: Emily Mason

Date: 10/14/2006


What exactly IS Zinc?



So what does that have to do with my cold?


·       One of the common, more recent claims is that zinc gluconate glycine (brand name Cold-EEZE) reduces the duration and severity of the common cold, if taken at the first signs of a cold.



What claims are out there?


Corporation, who produces and markets Cold-EEZE, claims that their unique formula of zinc lozenges is clinically proven to shorten the duration and severity of the common cold.   




The picture to the right is an exact copy of

a section of the back of the Cold-EEZE box.









This photo was found on the following

website as an indication of how well the

Cold-EEZE product works.




Sure, but can they back it up?


The Quigley Corporation refers to five studies as evidence that zinc gluconate glycine lozenges reduce the duration of the common cold. I have summarized two of them below. The reason I have chosen only two of the studies, rather than their 5 is because:

Ø      I was unable to locate the actual study for one on the list,

Ø      one was essentially a duplicate of an aforementioned one,

Ø      one dealt with the safety of the lozenges with regards to diabetics.


To see the Quigley Coropration’s interpretations of the three studies I did not summarize, you may go to:


The ones I have summarized are below:







What does the other research say?


It is necessary to review other research, because the Cold-EEZE manufacturers are likely to only include studies that support their hypothesis, which will in turn sell their product. Many other studies have been done on the effectiveness of zinc in reducing the duration of the common cold. I restricted my search of these studies to those that looked at the specific ionic zinc (zinc gluconate glycine) used in Cold-EEZE.


o       This study tested zinc gluconate lozenges as a possible treatment for common colds in a double-blind, placebo-controlled clinical trial

o       Subjects took one lozenge/placebo every 2 waking hours.

o       Results showed that after 7 days 86% of zinc-treated subjects had no symptoms, while only 46% of placebo-treated subjects exhibited no symptoms. [4]


o       Two randomized, placebo-controlled experiments were conducted.

o       In trial 1: subjects were given zinc gluconate lozenges 36 hours after they were infected with the cold virus.

o       In trial 2: subjects were given zinc lozenges 2 hours after they were infected with the cold virus.

o       The zinc gluconate lozenge did not reduce the severity or duration of symptoms in either trial  [5]


o       Outcome:  


Let it be noted however that upon further research, I discovered a potential explanation for this outcome. It could be a result of the formulations that the experimenters were using. More specifically, the experimenters could have been including another chemical in the formulation, and this chemical could be binding to the zinc, making it unable to bind with the virus [6].




Let’s take a deeper look into HOW it works…

·        Novick, Godfrey, Pollack, et al. (1997)

o       This proposes that free ionic zinc (Zn2+) binds with surface proteins and proteins of critical nerve endings on the human rhinovirus.

o       This binding would result in an interruption of nerve impulses and the blocking of HRV from binding to the somatic cells. This would interrupt HRV infection.  [7]

o       Study 2: Novick, Godfrey, Godfrey, et al. (1996) [8]




What are the side effects of taking so much zinc?


·        According to the Eby, Davis, and Halcomb study, which took note of adverse effects, they were infrequent. When they did occur they were usually minor and consisted mainly of offensive taste and irritation in the mouth [4].



To sum it all up…


            It appears that there is fairly sound evidence to indicate that zinc gluconate does have an effect on the duration of the common cold and possibly on the severity of it as well. However more research needs to be done on this topic, because of the contradictory nature of the studies which have been reported to date. So, while much of the research that has been conducted is promising, it’s necessary that more research be done to determine the mechanism of action and exactly what forms of zinc actually have a positive effect on the common cold.










  1. Bach, James F., MD. Prescription for Nutritional Healing, Second Edition. 1997.


  1. Mossad, S.; Macknin, M.; Mendendorp, S.; et al. Zinc Gluconate Lozenges for Treating the Common Cold. 1996


  1. McElroy, B.; Miller, S. An open-label, single-center, phase IV clinical study of the effectiveness of zinc gluconate glycine lozenges (COLD-EEZE) in reducing the duration and symptoms of the common cold in school-aged subjects. Am J Ther. 2003 Sep-Oct; 10(5): 324-29.


  1. Eby, G.; Davis, D.; Halcomb, W. Reduction in duration of common colds by zinc gluconate lozenges in a double-blind study. Antimicrobial Agents and Chemotherapy. 1984 January; 25(1): 20-24.


  1. Farr, B.; Conner, E.; Oleske, J.; et al. Two randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus colds. Antimicrobial Agents and Chemotherapy. 1987 August; 31(8): 1183-87


  1. Jackson, Jeffery L., MD; Peterson, Cecily MD. A Meta-analysis of Zinc Salts  and the Common Cold. Arch Inter Med. November 1997; 157(20): 2373-76.


  1. Novick, S.; Godfrey, J.; Pollack, R.; et al. Zinc induced suppression of inflammation in the respiratory tract, caused by infection with human rhinovirus and other irritants. Med Hypotheses. 1997; 49: 347-57


  1. Novick, S.; Godfrey, J.; Godfrey, N.; et al. How does zinc modify the common cold? Clinical observations and implications regarding mechanisms of action. Med Hypotheses. 1996; 46: 295-302



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