No strong evidence from trials that taking zinc can help improve the common cold cochraneconsumer.com
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Date: 2003, 21 Jul
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The review showed that there is no strong evidence to indicate that zinc lozenges reduce the duration of the common cold. People taking zinc lozenges were more likely to complain of mouth irritation, unpleasant taste, feeling sick and diarrhoea. More research is needed to determine if zinc lozenges can reduce the duration of the common cold and the potential for zinc lozenges to adversely effect health.
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"Zinc for the common cold"
by Marshall I
A substantive amendment to this systematic review was last made on Monday, 15 February 1999. Cochrane reviews are regularly checked and updated if necessary.
Background
Of the eight trials conducted since 1984 investigating the use of zinc in the treatment of the common cold, four have shown some benefit while the remainder have shown no benefit. Treatment masking and reduced bioavailability of zinc from some formulations have been claimed to influence the results reported. This review was undertaken to assess the overall usefulness of zinc as a treatment for the common cold.
Objectives
Interest in zinc as a treatment for the common cold has grown following the recent publication of several controlled trials. The objective of this review was to assess the effects of zinc lozenges for cold symptoms.
Search strategy
A search was made of the Cochrane Controlled Trials Register, MEDLINE, EMBASE and reference lists of articles. Searches were run to the end of 1997.
Selection criteria
Randomised double blind placebo-controlled trials of zinc for acute upper respiratory tract infection or cold.
Data collection and analysis
Two reviewers independently extracted data and assessed trial quality.
Main results
Seven trials involving 754 cases were included. With the exception of one study, the methodological quality was rated as medium to high. For most outcome measures different summary estimates were used across the studies to describe the duration, incidence and severity of respiratory symptoms. This limited the ability to pool results. Results from two trials (; ) suggested zinc lozenges reduced the severity and duration of cold symptoms. However, there was significant potential for bias, and further research is required to substantiate these findings. Overall, the results suggest that treatment with zinc lozenges did not reduce the duration of cold symptoms.
Reviewer's conclusions
Evidence of the effects of zinc lozenges for treating the common cold is inconclusive. Given the potential for treatment to produce side effects, the use of zinc lozenges to treat cold symptoms deserves further study.
[This abstract has been prepared centrally.]
Citation: Marshall I. Zinc for the common cold (Cochrane Review). In: The Cochrane Library, 2, 2001. Oxford: Update Software.
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This is an abstract of a regularly updated, systematic review prepared and maintained by the Cochrane Collaboration. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).
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File Reference: ab001364
Cochrane Consumer Network - 11/21/03 3:40:28 AM
Zinc for the common cold - Marshall I |
