Zinc Lozenges Shorten Duration of the Common Cold

A new study shows strong evidence that the zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses.

Health Studies Journal | Americans spend over one billion dollars annually on nonprescription treatments for coughs and colds, including antipyretics, antihistamines, cough preparations, and decongestants in various combinations. Although these agents may help the symptoms of colds and flu to subside gradually, they do not address the underlying condition, including immune and nutrition status. Also, many of the agents used conventionally for colds and flu may cause unwanted side effects such as insomnia, hyper-excitability, dry mouth, constipation, drowsiness, or interact with prescription medications. As an alternative to standard over-the-counter cold remedies, different preparations of the herb echinacea are well marketed.

Zinc is necessary for the functioning of over 300 different enzymes and, as such, it plays a vital role in an enormous number of biological processes. Zinc is widely distributed in microorganisms, plants, and animals. In humans, the highest concentrations of zinc are found in the liver, pancreas, kidneys, bone, and muscles. Zinc is highly concentrated in parts of the eye, prostate gland, sperm, skin, hair, and nails. Zinc helps regulate a wide variety of immune system functions and it may stimulate anti-viral activity. Because of these benefits, it has been studied for use as a treatment for the common cold. The best dietary sources of zinc are lean meats, liver, eggs, and seafood (especially oysters). Whole grain breads and cereals are also good sources of zinc.

A meta-analysis, published in the Open Respiratory Medicine Journal, examined whether zinc lozenges could be effective in shortening the duration of the common cold. The Medline, Scopus and Cochrane Central Register of Controlled Trials data bases were searched for placebo-controlled trials examining the effect of zinc lozenges on common cold duration. Five of the total 13 trials used a total daily zinc dose of less than 75 mg were found to have no effect on the common cold. Another five trials used zinc salts other than acetate in daily doses of over 75 mg resulting in a 20 percent reduction in the duration of colds. Three trials used zinc acetate in daily doses of over 75 mg resulting in a 42 percent reduction in the duration of colds. The authors concluded "This study shows strong evidence that the zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses. The effects of zinc lozenges should be further studied to determine the optimal lozenge compositions and treatment strategies."1

1 Hemila H. Zinc lozenges may shorten the duration of colds: a systematic review. Open Respir Med J. 2011:51-8.