Zinc and the Common Cold

by Harri Hemilä

Department of Public Health
University of Helsinki, Finland
harri.hemila@helsinki.fi
https://www.mv.helsinki.fi/home/hemila
Jan 31, 2025

Systematic reviews and RCT
Reviews
Letters
Problems with the Cochrane review on on zinc and the common cold
Problems with two other reviews on on zinc and the common cold

Systematic reviews and statistical analyses and an RCT

Hemilä H, Chalker E.
Shortcomings in the Cochrane review on zinc for the common cold (2024).
Front Med (Lausanne). 2024
https://doi.org/10.3389/fmed.2024.1470004
https://pmc.ncbi.nlm.nih.gov/articles/PMC11521859

Hemilä H, Pirinen M.
Estimating quantile treatment effect on the original scale of the outcome variable: a case study of common cold treatments.
arXiv 2023
https://doi.org/10.48550/arXiv.2310.17917

Hemilä H, Chalker E, Tukiainen J.
Response: Commentary: Quantile treatment effect of zinc lozenges on common cold duration: a novel approach to analyze the effect of treatment on illness duration.
Front Pharmacol. 2024
https://doi.org/10.3389/fphar.2024.1335784
https://pmc.ncbi.nlm.nih.gov/articles/PMC11035776

Hemilä H, Chalker E, Tukiainen J.
Quantile treatment effect of zinc lozenges on common cold duration: a novel approach to analyze the effect of treatment on illness duration.
Front Pharmacol. 2022
https://doi.org/10.3389/fphar.2022.817522
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc8844493
https://pubmed.ncbi.nlm.nih.gov/35177991

Hemilä H, Haukka J, Alho M, Vahtera J, Kivimä i M.
Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial.
BMJ Open 2020
https://doi.org/10.1136/bmjopen-2019-031662
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc7045205
https://www.ncbi.nlm.nih.gov/pubmed/31980506

Hemilä H.
Duration of the common cold and similar continuous outcomes should be analyzed on the relative scale: a case study of two zinc lozenge trials.
BMC Medical Research Methodology 2017;17:82
https://doi.org/10.1186/s12874-017-0356-y
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5427521
https://www.ncbi.nlm.nih.gov/pubmed/28494765

Hemilä H, Fitzgerald JT, Petrus EJ, Prasad A.
Zinc acetate lozenges may improve the recovery rate of common cold patients: an individual patient data meta-analysis
Open Forum Infectious Diseases 2017;4(2):ofx059.
https://doi.org/10.1093/ofid/ofx059
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5410113
https://www.ncbi.nlm.nih.gov/pubmed/28480298

Hemilä H.
Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage.
JRSM Open 2017;8(5):2054270417694291.
https://doi.org/10.1177/2054270417694291
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5418896
https://www.ncbi.nlm.nih.gov/pubmed/28515951

Hemilä H, Petrus EJ, Fitzgerald JT, Prasad A.
Zinc acetate lozenges for treating the common cold: an individual patient data meta-analysis.
Br J Clin Pharmacology 2016;82:1393-1398.
https://doi.org/10.1111/bcp.13057
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5061795
https://www.ncbi.nlm.nih.gov/pubmed/27378206

Hemilä H, Chalker E.
The effectiveness of high dose zinc acetate lozenges on various common cold symptoms: a meta-analysis.
BMC Family Practice 2015;16:24
https://doi.org/10.1186/s12875-015-0237-6
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4359576
https://www.ncbi.nlm.nih.gov/pubmed/25888289

Hemilä H.
Zinc lozenges may shorten the duration of colds: a systematic review.
Open Respir Med J 2011;5:51-58
https://doi.org/10.2174/1874306401105010051
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136969
https://www.ncbi.nlm.nih.gov/pubmed/21769305

Reviews

Hemilä H.
Vitamins and minerals [book chapter].
In: "Common cold " (Eccles R, Weber O, eds.) Birkhauser Verlag, 2009:275-307
   Abstract and references:
https://www.mv.helsinki.fi/home/hemila/birkhauser
   Available at:
https://doi.org/10.1007/978-3-7643-9912-2_13
https://doi.org/10.1007/978-3-7643-9912-2
https://www.amazon.com/Common-Birkh%C3%A4user-Advances-Infectious-Diseases/dp/3764398949
https://www.barnesandnoble.com/w/common-cold-ronald-eccles/1136783297
    A manuscript version:
https://helda.helsinki.fi/handle/10138/228060

Letters and comments

Hemilä H, Chalker E.
Zinc and coronavirus disease.
Clin Infect Dis. 2023
https://doi.org/10.1093/cid/ciad078

Hemilä H, Chalker E.
Pitfalls in choosing data examples for methodological work: Bayesian approaches to a fixed effects meta-analysis of zinc lozenges for the common cold.
Res Synth Methods. 2022
https://doi.org/10.1002/jrsm.1601

Hemilä H, Chalker E.
Vitamin C and zinc lozenges for COVID-19?
J Am Pharm Assoc (2003). 2021
https://doi.org/10.1016/j.japh.2021.05.018
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc8163692/

Hemilä H.
Common Cold Treatment Using Zinc.
JAMA. 2015;314(7):730.
https://doi.org/10.1001/jama.2015.8174
https://www.ncbi.nlm.nih.gov/pubmed/26284728

    The above JAMA letter pointed out problems in an JAMA article by Das and Singh, which was a summary of their Cochrane review.
    As their Cochrane review was withdrawn, their JAMA article was also retracted:
    https://doi.org/10.1001/jama.2016.18134
    https://www.ncbi.nlm.nih.gov/pubmed/28027374

More detailed problems in the Das and Singh JAMA article were described in a longer document:
Hemilä H.
Problems with the calculations in the JAMA Clinical Evidence Synopsis “Oral Zinc for the Common Cold” by Das and Singh (2014). 2015.
Repository of the University of Helsinki
https://hdl.handle.net/10138/153617
https://doi.org/10.5281/zenodo.6393781

Hemilä H.
Zinc lozenges and vitamin C for the common cold are not examples of placebo effect in action.
J Clin Epidemiol. 2015;68(12):1524-1525.
https://doi.org/10.1016/j.jclinepi.2015.05.012
https://hdl.handle.net/10138/228079
https://www.ncbi.nlm.nih.gov/pubmed/26071891

Hemilä H.
Zinc lozenges may shorten common cold duration.
Expert Review of Respiratory Medicine 2012;6:253-254
https://doi.org/10.1586/ers.12.30

Hemilä H.
Zinc acetate lozenges may shorten common cold duration by up to 40%
https://www.cmaj.ca/content/184/10/E551/tab-e-letters#zinc-acetate-lozenges-may-shorten-common-cold-duration-by-up-to-40
https://helda.helsinki.fi/handle/10138/228083
https://doi.org/10.5281/zenodo.6395777

Problems with various Cochrane reviews on zinc and the common cold

Problems in the 2024 version of Cochrane review:

Longer version describing the details of the flaws:

Hemilä H.
Shortcomings in the Cochrane review on zinc and the common cold by Nault et al. (2024).
Zenodo.
https://doi.org/10.5281/zenodo.137625 69

Problems in the 2013 version of Cochrane review:
Hemilä H.
Concerns about unattributed copying of text and data, and about numerous other problems in the Cochrane review “Zinc for the Common Cold” by Singh M, Das RR (2013). 2015
Repository of the University of Helsinki
https://hdl.handle.net/10138/153180
https://doi.org/10.5281/zenodo.6394115

    The above comment led to the withdrawal of the Cochrane review, see:
    https://www.cochrane.org/CD001364/ARI_zinc-common-cold
    https://doi.org/10.1002/14651858.CD001364.pub5

Problems in the 2011 version of Cochrane review:
Hemilä H.
The zinc for the common cold review by Singh and Das has a number of problems which should be considered when the review is next time updated.
[Feedback on the Cochrane review “Zinc for the common cold review” by Singh and Das]. 2011.
Cochrane Database of Systematic Reviews CD001364 [Feedback 5 September 2011]
Repository of the University of Helsinki
https://helda.helsinki.fi/handle/10138/39188
https://doi.org/10.13140/2.1.4688.2081

Problems with two other reviews on zinc and the common cold

Hemilä H.
Zinc acetate lozenges may shorten common cold duration by up to 40%. CMAJ 2012 [e-letter May 28, 2012]
[Comments on: https://doi.org/10.1503/cmaj.111990]
Repository of the University of Helsinki
https://www.cmaj.ca/content/184/10/E551/tab-e-letters#zinc-acetate-lozenges-may-shorten-common-cold-duration-by-up-to-40
https://helda.helsinki.fi/handle/10138/228083
https://doi.org/10.5281/zenodo.6395777

Hemilä H.
Zinc and the common cold: problems in the review by Caruso et al. (2007). 2013.
[Comments on: Caruso TJ, Prober CG, Gwaltney JM Jr. Treatment of naturally acquired common colds with zinc: a structured review. Clin Infect Dis 2007;45:569-74 https://doi.org/10.1086/520031 ]
Repository of the University of Helsinki
https://helda.helsinki.fi/handle/10138/40817
https://doi.org/10.5281/zenodo.6405360