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BACKGROUND: The common cold is one of the most widespread illnesses and is a leading cause of visits to the doctor and absenteeism from school and work. Trials conducted in high-income countries since 1984 investigating the role of zinc for the common cold symptoms have had mixed results. Inadequate treatment masking and reduced bioavailability of zinc from some formulations have been cited as influencing results. OBJECTIVES: To assess whether zinc (irrespective of the zinc salt or formulation used) is efficacious in reducing the incidence, severity and duration of common cold symptoms. In addition, we aimed to identify potential sources of heterogeneity in results obtained and to assess their clinical significance. SEARCH METHODS: In this updated review, we searched CENTRAL (2012, Issue 12), MEDLINE (1966 to January week 2, 2013), EMBASE (1974 to January 2013), CINAHL (1981 to January 2013), Web of Science (1985 to January 2013), LILACS (1982 to January 2013), WHO ICTRP and clinicaltrials.gov. SELECTION CRITERIA: Randomised, double-blind, placebo-controlled trials using zinc for at least five consecutive days to treat, or for at least five months to prevent the common cold. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed trial quality. MAIN RESULTS: Five trials were identified in the updated searches in January 2013 and two of them did not meet our inclusion criteria. We included 16 therapeutic trials (1387 participants) and two preventive trials (394 participants). Intake of zinc was associated with a significant reduction in the duration (days) (mean difference (MD) -1.03, 95% confidence interval (CI) -1.72 to -0.34) (P = 0.003) (I(2) statistic = 89%) but not the severity of common cold symptoms (MD -1.06, 95% CI -2.36 to 0.23) (P = 0.11) (I(2) statistic = 84%). The proportion of participants who were symptomatic after seven days of treatment was significantly smaller (odds ratio (OR) 0.45, 95% CI 0.20 to 1.00) (P = 0.05) than those in the control, (I(2 )statistic = 75%). The incidence rate ratio (IRR) of developing a cold (IRR 0.64, 95% CI 0.47 to 0.88) (P = 0.006) (I(2) statistic = 88%), school absence (P = 0.0003)

BACKGROUND: The common cold is one of the most widespread illnesses and is a leading cause of visits to the doctor and absenteeism from school and work. Trials conducted since 1984 investigating the role of zinc for the common cold symptoms have had mixed results. Inadequate treatment masking and reduced bioavailability of zinc from some formulations have been cited as influencing results. OBJECTIVES: To assess the effect of zinc on common cold symptoms. SEARCH STRATEGY: We searched CENTRAL (2010, Issue 2) which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to May week 3, 2010) and EMBASE (1974 to June 2010). SELECTION CRITERIA: Randomised, double-blind, placebo-controlled trials using zinc for at least five consecutive days to treat, or for at least five months to prevent the common cold. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed trial quality. MAIN RESULTS: We included 13 therapeutic trials (966 participants) and two preventive trials (394 participants). Intake of zinc is associated with a significant reduction in the duration (standardized mean difference (SMD) -0.97; 95% confidence interval (CI) -1.56 to -0.38) (P = 0.001), and severity of common cold symptoms (SMD -0.39; 95% CI -0.77 to -0.02) (P = 0.04). There was a significant difference between the zinc and control group for the proportion of participants symptomatic after seven days of treatment (OR 0.45; 95% CI 0.2 to 1.00) (P = 0.05). The incidence rate ratio (IRR) of developing a cold (IRR 0.64; 95% CI 0.47 to 0.88) (P = 0.006), school absence (P = 0.0003) and prescription of antibiotics (P < 0.00001) was lower in the zinc group. Overall adverse events (OR 1.59; 95% CI 0.97 to 2.58) (P = 0.06), bad taste (OR 2.64; 95% CI 1.91 to 3.64) (P < 0.00001) and nausea (OR 2.15; 95% CI 1.44 to 3.23) (P = 0.002) were higher in the zinc group. AUTHORS' CONCLUSIONS: Zinc administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people. When supplemented for at least five months, it reduces cold incidence, school absenteeism and prescription of antibiotics in children. Th

Several controlled clinical trials have shown that zinc gluconate glycine lozenges can reduce symptom severity and duration of symptoms in patients with the common cold. Over-the-counter zinc lozenges are used commonly by the general population, including people with diabetes. The purpose of this study was to assess the effects of sugar-free Cold-Eeze (The Quigley Corp., Doylestown, PA), a commonly used zinc preparation, on glucose control in patients maintained on stable antidiabetic therapy. Forty-eight patients with either type 1 (n = 3) or type 2 (n = 45) diabetes were randomized in a 3:1 ratio to receive either zinc lozenges (four to six lozenges/day for 10 days) or matching placebo. The primary endpoint was change in serum fructosamine concentration. Secondary endpoints included daily home glucose and fasting blood glucose monitoring (baseline, days 10 and 21). The mean age for all patients was 54 years (range, 25 to 76), with slightly more women (60%). The treatment groups did not differ with respect to age, sex, body mass index, duration of diabetes, baseline hemoglobin A1C level, or fasting plasma glucose level. The patients treated with placebo (n = 13) and zinc (n = 34) had similar fructosamine levels (mean +/- SD) at baseline (318 +/- 90 versus 297 +/- 86 micromol/l, respectively). After 10 days of dosing, both groups showed modest reductions in serum fructosamine (-7 +/- 42 and -9 +/- 90 micromol/l). These changes were not statistically significant. In conclusion, these findings suggest that sugar-free zinc lozenges can be administered safely to patients with diabetes without deleterious effects on glycemic control.

OBJECTIVE: To summarize and critique the medical literature on the use of zinc lozenges for treatment of the common cold. DATA SOURCES: MEDLINE searches (January 1966-June 1997) identified human clinical trials on the use of zinc lozenges for the treatment of the common cold. Bibliographies were also reviewed for relevant articles. STUDY SELECTION: Double-blind, placebo-controlled trials of zinc lozenges in adults for the treatment of the common cold, with the clinical end points of reduction in duration and/or severity of cold symptoms. DATA EXTRACTION: All double-blind placebo-controlled, human clinical trials on the use of zinc lozenges for the treatment of the common cold were included. DATA SYNTHESIS: The use of zinc lozenges in the treatment of the common cold has been suggested to reduce the duration and severity of cold symptoms. Of eight double-blind, placebo-controlled trials, four found zinc lozenges to be effective, while the other four reported no difference between zinc and placebo therapy. Potential reasons for the discrepancy between the results of these trials include inadequate placebo control, formulation of the lozenge, and the dose of zinc used. Common adverse effects include unpleasant taste, mouth irritation, and nausea. CONCLUSIONS: Treatment of the common cold with zinc gluconate lozenges, using adequate doses of elemental zinc, may be effective in reducing duration and severity of cold symptoms. The benefit appears to be maximal if the lozenges are started immediately after the onset of symptoms. The formulation of the lozenges also appears to be important because the addition of citric acid or tartaric acid may reduce efficacy due to chelation of zinc ion. Although zinc gluconate lozenges have dominated clinical trials thus far, further studies are needed to demonstrate the efficacy of zinc acetate lozenges and to determine whether their adverse effect profile is more favorable to that of zinc gluconate lozenges. Patients should play an important role in the decision-making process and must decide whether the benefit gained from treatment with zinc lozenges outweighs the potential adverse effects.

Update of Cochrane Database Syst Rev. 2013 Jun 18;(6):CD001364. doi: 10.1002/14651858.CD001364.pub4. September 2016 updated withdrawal notice This Cochrane Review was withdrawn in April 2015, and this withdrawal notice was updated in September 2016. The review was withdrawn as result of comments submitted via the Cochrane Library by Harri Hemilä in February 2015. Hemilä identified multiple errors in this Cochrane Review and made allegations of plagiarism of text and data from a previously published systematic review (Hemilä H. Zinc Lozenges may shorten the duration of colds: a systematic review. Open Respiratory Medicine Journal 2011;5:51‐58. dx.doi.org/10.2174/1874306401105010051). The comments referred to the version of this review first published in June 2013 (Singh M, Das RR. Zinc for the common cold. Cochrane Database of Systematic Reviews 2013;(6):CD001364. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001364.pub4/full). The Cochrane Acute Respiratory Infections Group, which maintains the review, withdrew the review in April 2015, pending an assessment of the errors reported, and the group referred the allegations of plagiarism to the Editor in Chief. The Editor in Chief notified the authors of the concerns, and followed the Committee for Publication Ethics (COPE) guidelines. Replication of text was identified in the Cochrane Review. This was limited to copying of short phrases and was acknowledged by the authors. The level of text plagiarism was minor and at a level that would be addressed by a correction. The Editor in Chief carried out further investigation into the alleged plagiarism of data, with the co‐operation of the review authors, who provided supplementary information in support of their work. The allegations related to the derivation of means and standard deviations of data from some of the included studies. Although the authors acknowledge and cite the Hemilä 2011 review, the Editor in Chief considered that the authors’ explanation regarding some similarities in presented data between the two reviews was not conclusive. This version of the review will therefore remain withdrawn. April 2015 withdrawal notice This review was withdrawn d

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 (04 - Mossad; 08 - Smith) 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. AUTHORS' 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.].

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 (04 - Mossad; 08 - Smith) 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.

BACKGROUND: The common cold is an acute, self-limiting viral respiratory illness. Symptoms include nasal congestion and mucus discharge, sneezing, sore throat, cough, and general malaise. Given the frequency of colds, they are a public health burden and a significant cause of lost work productivity and school absenteeism. There are no established interventions to prevent colds or shorten their duration. However, zinc supplements are commonly recommended and taken for this purpose. OBJECTIVES: To assess the effectiveness and safety of zinc for the prevention and treatment of the common cold. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, CINAHL, and LILACS to 22 May 2023, and searched Web of Science Core Collection and two trials registries to 14 June 2023. We also used reference checking, citation searching, and contact with study authors to identify additional studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) in children or adults that tested any form of zinc against placebo to prevent or treat the common cold or upper respiratory infection (URTI). We excluded zinc interventions in which zinc was combined with other minerals, vitamins, or herbs (e.g. a multivitamin, or mineral supplement containing zinc). DATA COLLECTION AND ANALYSIS: We used the Cochrane risk of bias tool to assess risks of bias, and GRADE to assess the certainty of the evidence. We independently extracted data. When necessary, we contacted study authors for additional information. We assessed zinc (type and route) with placebo in the prevention and treatment of the common cold. Primary outcomes included the proportion of participants developing colds (for analyses of prevention trials only), duration of cold (measured in days from start to resolution of the cold), adverse events potentially due to zinc supplements (e.g. unpleasant taste, loss of smell, vomiting, stomach cramps, and diarrhoea), and adverse events considered to be potential complications of the common cold (e.g. respiratory bacterial infections). MAIN RESULTS: We included 34 studies (15 prevention, 19 treatment) involving 8526 participants. Twenty-two studies were conducted on adults and 12 stu

BACKGROUND: Functional iron deficiency facilitates allergy development and amplifies the symptom burden in people experiencing allergies. Previously we selectively delivered micronutrients to immune cells with β-lactoglobulin as carrier (holoBLG), resulting in immune resilience and allergy prevention. OBJECTIVE: The clinical efficacy of a food for special medical purposes-lozenge containing β-lactoglobulin with iron, polyphenols, retinoic acid, and zinc (holoBLG lozenge) was assessed in allergic women. METHODS: In a randomized, double-blind, placebo-controlled pilot study, grass- and/or birch pollen-allergic women (n = 51) were given holoBLG or placebo lozenges over 6 months. Before and after dietary supplementation, participants were nasally challenged and the blood was analyzed for immune and iron parameters. Daily symptoms, medications, pollen concentrations, and well-being were recorded by an electronic health application. RESULTS: Total nasal symptom score after nasal provocations improved by 42% in the holoBLG group versus 13% in the placebo group. The combined symptom medication score during the birch peak and entire season as well as the entire grass pollen season improved in allergic subjects supplemented with the holoBLG lozenge by 45%, 31%, and 40%, respectively, compared with the placebo arm. Participants ingesting the holoBLG lozenge had improved iron status with increased hematocrit values, decreased red cell distribution width, and higher iron levels in circulating CD14+ cells compared with the placebo group. CONCLUSIONS: Targeted micronutrition with the holoBLG lozenge seemed to be effective in elevating the labile iron levels in immune cells and reducing the symptom burden in allergic women in this pilot study. The underlying allergen-independent mechanism provides evidence that dietary nutritional supplementation of the immune system is one of the ways to combat atopy.

Zinc is a relevant nutritional factor for the whole life of an organism because it affects the inflammatory/immune response and antioxidant activity, leading to a healthy state. Despite its important function, the dietary intake of zinc is inadequate in elderly. Possible interventions include food fortification because it does not require changes in dietary patterns, the cost is low and it can reach a large portion of the elderly population, including very old subjects. Studies evaluating the impact of Zn-fortified foods on functional parameters in elderly, in particular, in very old individuals, are missing. The objective of this study was to evaluate the efficacy of consumption of a zinc-fortified drinking skim milk (Zn-FMilk) for a period of 2 months in comparison to standard non-fortified milk (No-FMilk) on some biochemical parameters, zinc status, inflammatory/immune response and on a key parameter of the T cell-mediated immunity (thymulin hormone) in healthy very old subjects. The treatment with zinc-fortified milk (Zn-FMilk) is a good omen to increase the cell-mediated immunity in very old age represented by thymulin activity and some cytokine (IL-12p70, IFN-γ) release. At clinical level, a good healthy state occurs in 70 % of the subjects with no hospitalization after 1 year of the follow-up in comparison to very old control subjects that did not participate to crossover design. In conclusion, the Zn-FMilk can be considered a good functional food for elderly, including older people. It might be a good replacement to the zinc tablets or lozenges taking into account the attitude of old people to uptake milk as a preferential food.

BACKGROUND: Effects of treatments on continuous outcomes are commonly estimated using the mean difference (in units of measurement) or the ratio of means (percentages), each providing a single average effect across the study population. Quantile treatment effect (QTE) analysis is more informative as it estimates the effect of treatment across the whole population. A limitation of the standard QTE is its presentation over control group quantiles, which can hinder interpretability. Presentation of the effect over the measurement units would often be more informative. METHODS: We introduce a method to estimate back-transformed QTE (BQTE), which presents QTEs as a function of the original outcome values in the control group. This approach uses a bootstrap algorithm to estimate both the BQTE curve and its uncertainty. We further derive informative bounds for the average treatment effect at the upper and lower tails of the distribution. The method was applied to 3 datasets on the treatment of the common cold: zinc gluconate lozenges, zinc acetate lozenges, and nasal carrageenan. RESULTS: Across all 3 datasets, BQTE revealed substantial heterogeneity in treatment effects on the units of measurement scale (days). Specifically, shorter colds showed smaller average effects than longer colds, indicating that the assumption of a constant mean difference across the distribution may be inappropriate. In all cases, the relative scale provided a better summary of the BQTE distribution than the mean difference. CONCLUSIONS: The BQTE method enhances the interpretability of QTEs by presenting results on the outcome's original scale. It provides a nuanced understanding of how the average treatment effect varies across the distribution. BQTE is particularly suited for analyzing continuous clinical outcomes such as illness duration or hospital stay and offers a valuable complement to the standard effect size measures in individual-patient data meta-analysis and clinical trial reporting. © 2025. The Author(s).

91. Front Med (Lausanne). 2024 Oct 16;11:1470004. doi: 10.3389/fmed.2024.1470004. eCollection 2024. Shortcomings in the Cochrane review on zinc for the common cold (2024). Hemilä H(1), Chalker E(2). Author information: (1)Department of Public Health, University of Helsinki, Helsinki, Finland. (2)National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT, Australia. DOI: 10.3389/fmed.2024.1470004 PMCID: PMC11521859 PMID: 39478818 Conflict of interest statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Comment in Res Synth Methods. 2023 Jan;14(1):2. doi: 10.1002/jrsm.1600.

OBJECTIVE: To compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment and to examine the dose-dependency of the effect. DESIGN: Meta-analysis. SETTING: Placebo-controlled zinc lozenge trials, in which the zinc dose was > 75 mg/day. The pooled effect of zinc lozenges on common cold duration was calculated by using inverse-variance random-effects method. PARTICIPANTS: Seven randomised trials with 575 participants with naturally acquired common colds. MAIN OUTCOME MEASURE: Duration of the common cold. RESULTS: The mean common cold duration was 33% (95% CI 21% to 45%) shorter for the zinc groups of the seven included trials. Three trials that used lozenges composed of zinc acetate found that colds were shortened by 40% and four trials that used zinc gluconate by 28%. The difference between the two salts was not significant: 12 percentage points (95% CI: -12 to + 36). Five trials used zinc doses of 80-92 mg/day, common cold duration was reduced by 33%, and two trials used zinc doses of 192-207 mg/day and found an effect of 35%. The difference between the high-dose and low-dose zinc trials was not significant: 2 percentage points (95% CI: -29 to + 32). CONCLUSIONS: Properly composed zinc gluconate lozenges may be as effective as zinc acetate lozenges. There is no evidence that zinc doses over 100 mg/day might lead to greater efficacy in the treatment of the common cold. Common cold patients may be encouraged to try zinc lozenges for treating their colds. The optimal lozenge composition and dosage scheme need to be investigated further.

BACKGROUND: The relative scale has been used for decades in analysing binary data in epidemiology. In contrast, there has been a long tradition of carrying out meta-analyses of continuous outcomes on the absolute, original measurement, scale. The biological rationale for using the relative scale in the analysis of binary outcomes is that it adjusts for baseline variations; however, similar baseline variations can occur in continuous outcomes and relative effect scale may therefore be often useful also for continuous outcomes. The aim of this study was to determine whether the relative scale is more consistent with empirical data on treating the common cold than the absolute scale. METHODS: Individual patient data was available for 2 randomized trials on zinc lozenges for the treatment of the common cold. Mossad (Ann Intern Med 125:81-8, 1996) found 4.0 days and 43% reduction, and Petrus (Curr Ther Res 59:595-607, 1998) found 1.77 days and 25% reduction, in the duration of colds. In both trials, variance in the placebo group was significantly greater than in the zinc lozenge group. The effect estimates were applied to the common cold distributions of the placebo groups, and the resulting distributions were compared with the actual zinc lozenge group distributions. RESULTS: When the absolute effect estimates, 4.0 and 1.77 days, were applied to the placebo group common cold distributions, negative and zero (i.e., impossible) cold durations were predicted, and the high level variance remained. In contrast, when the relative effect estimates, 43 and 25%, were applied, impossible common cold durations were not predicted in the placebo groups, and the cold distributions became similar to those of the zinc lozenge groups. CONCLUSIONS: For some continuous outcomes, such as the duration of illness and the duration of hospital stay, the relative scale leads to a more informative statistical analysis and more effective communication of the study findings. The transformation of continuous data to the relative scale is simple with a spreadsheet program, after which the relative scale data can be analysed using standard meta-analysis software. The option for the analysis of re

BACKGROUND: A previous meta-analysis of 3 zinc acetate lozenge trials estimated that colds were on average 40% shorter for the zinc groups. However, the duration of colds is a time outcome, and survival analysis may be a more informative approach. The objective of this individual patient data (IPD) meta-analysis was to estimate the effect of zinc acetate lozenges on the rate of recovery from colds. METHODS: We analyzed IPD for 3 randomized placebo-controlled trials in which 80-92 mg/day of elemental zinc were administered as zinc acetate lozenges to 199 common cold patients. We used mixed-effects Cox regression to estimate the effect of zinc. RESULTS: Patients administered zinc lozenges recovered faster by rate ratio 3.1 (95% confidence interval, 2.1-4.7). The effect was not modified by age, sex, race, allergy, smoking, or baseline common cold severity. On the 5th day, 70% of the zinc patients had recovered compared with 27% of the placebo patients. Accordingly, 2.6 times more patients were cured in the zinc group. The difference also corresponds to the number needed to treat of 2.3 on the 5th day. None of the studies observed serious adverse effects of zinc. CONCLUSIONS: The 3-fold increase in the rate of recovery from the common cold is a clinically important effect. The optimal formulation of zinc lozenges and an ideal frequency of their administration should be examined. Given the evidence of efficacy, common cold patients may be instructed to try zinc acetate lozenges within 24 hours of onset of symptoms. © The Author 2017. Published by Oxford University Press on behalf of Infectious Diseases Society of America.

AIMS: The aim of this study was to determine whether the allergy status and other characteristics of common cold patients modify the effects of zinc acetate lozenges. METHODS: We had available individual patient data for three randomized placebo-controlled trials in which zinc acetate lozenges were administered to common cold patients. We used both one stage and two stage meta-analysis to estimate the effects of zinc lozenges. RESULTS: The total number of common cold patients was 199, the majority being females. Eighty percent of them fell into the age range 20-50 years. One third of the patients had allergies. The one stage meta-analysis gave an overall estimate of 2.73 days (95% CI 1.8, 3.3 days) shorter colds by zinc acetate lozenge usage. The two stage meta-analysis gave an estimate of 2.94 days (95% CI 2.1, 3.8 days) reduction in common cold duration. These estimates are to be compared with the 7 day average duration of colds in the three trials. The effect of zinc lozenges was not modified by allergy status, smoking, baseline severity of the common cold, age, gender or ethnic group. CONCLUSION: Since the effects of zinc acetate lozenges were consistent between the compared subgroups, the overall estimates for effect seemed applicable over a wide range of common cold patients. While the optimal composition of zinc lozenges and the best frequency of their administration should be further investigated, given the current evidence of efficacy, common cold patients may be encouraged to try zinc lozenges for treating their colds. © 2016 The British Pharmacological Society.

BACKGROUND: A previous meta-analysis found that high dose zinc acetate lozenges reduced the duration of common colds by 42%, whereas low zinc doses had no effect. Lozenges are dissolved in the pharyngeal region, thus there might be some difference in the effect of zinc lozenges on the duration of respiratory symptoms in the pharyngeal region compared with the nasal region. The objective of this study was to determine whether zinc acetate lozenges have different effects on the duration of common cold symptoms originating from different anatomical regions. METHODS: We analyzed three randomized trials on zinc acetate lozenges for the common cold administering zinc in doses of 80-92 mg/day. All three trials reported the effect of zinc on seven respiratory symptoms, and three systemic symptoms. We pooled the effects of zinc lozenges for each symptom and calculated point estimates and 95% confidence intervals (95% CI). RESULTS: Zinc acetate lozenges shortened the duration of nasal discharge by 34% (95% CI: 17% to 51%), nasal congestion by 37% (15% to 58%), sneezing by 22% (-1% to 45%), scratchy throat by 33% (8% to 59%), sore throat by 18% (-10% to 46%), hoarseness by 43% (3% to 83%), and cough by 46% (28% to 64%). Zinc lozenges shortened the duration of muscle ache by 54% (18% to 89%), but there was no difference in the duration of headache and fever. CONCLUSIONS: The effect of zinc acetate lozenges on cold symptoms may be associated with the local availability of zinc from the lozenges, with the levels being highest in the pharyngeal region. However our findings indicate that the effects of zinc ions are not limited to the pharyngeal region. There is no indication that the effect of zinc lozenges on nasal symptoms is less than the effect on the symptoms of the pharyngeal region, which is more exposed to released zinc ions. Given that the adverse effects of zinc in the three trials were minor, zinc acetate lozenges releasing zinc ions at doses of about 80 mg/day may be a useful treatment for the common cold, started within 24 hours, for a time period of less than two weeks.

BACKGROUND: A number of controlled trials have examined the effect of zinc lozenges on the common cold but the findings have diverged. The purpose of this study was to examine whether the total daily dose of zinc might explain part of the variation in the results. METHODS: The Medline, Scopus and Cochrane Central Register of Controlled Trials data bases were searched for placebocontrolled trials examining the effect of zinc lozenges on common cold duration. Two methods were used for analysis: the P-values of the trials were combined by using the Fisher method and the results of the trials were pooled by using the inverse-variance method. Both approaches were used for all the identified trials and separately for the low zinc dose and the high zinc dose trials. RESULTS: Thirteen placebo-controlled comparisons have examined the therapeutic effect of zinc lozenges on common cold episodes of natural origin. Five of the trials used a total daily zinc dose of less than 75 mg and uniformly found no effect. Three trials used zinc acetate in daily doses of over 75 mg, the pooled result indicating a 42% reduction in the duration of colds (95% CI: 35% to 48%). Five trials used zinc salts other than acetate in daily doses of over 75 mg, the pooled result indicating a 20% reduction in the duration of colds (95% CI: 12% to 28%). CONCLUSIONS: 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.

OBJECTIVES: To review the seven Cochrane reviews of non-antibiotic treatment for the common cold. METHODS: Each Cochrane review was read and summarized, and results presented as relative risks and, where possible, numbers needed to treat. RESULTS: The main theme that runs through these Cochrane reviews is the variable quality of the primary studies. In general, the reviewers are fairly cautious about the benefits of any of the treatments other than first-dose decongestants and antihistamine-decongestant combinations. For antihistamines alone, the reviewers were clear about the lack of efficacy except in the high-quality studies in which a global improvement in symptoms was noted. Some studies were statistically significant, but the Cochrane reviewers were guarded about how clinically significant they were. For Echinacea, problems were found with the quality of the studies and the wide range of different forms of this substance. Heated humidified air seemed to be effective in the UK and Israel, but not the USA, making definitive statements about efficacy difficult. Over-the-counter medication for cough seemed to have no documented benefit in children under the age of 5 years. Letosteine (a mucolytic) may be effective in children but is not available in the UK. Bisolvon (a mucolytic) was found to be effective for cough in only one study. For older children and adults, dextromethorphan may be effective (two out of three studies showed benefit), and guiafenesin (an expectorant) showed mixed benefit in two trials. Dexbrompheniramine (a sedating antihistamine)/pseudoephedrine (6 mg/120 mg twice daily for 1 week) was significantly more effective than placebo for severity of cough, whereas, in another study, loratadine (a non-sedating antihistamine)/pseudoephedrine (5 mg/120 mg twice daily for 4 days) did not show any difference between the study groups. Vitamin C may have a small role in preventing the common cold, with possibly a greater role in high-intensity physical activity and sub-arctic conditions. Zinc lozenges seemed to be effective, but the issue of unblinding due to taste was a methodological issue of concern to the reviewers. The benefits and harms are calc