Zinc Lozenges Research Articles

Evidence-based treatment of the common cold with zinc lozenges

Evidence-based treatment of the common cold with zinc lozenges

Response: Commentary: Quantile treatment effect of zinc lozenges on common cold duration: a novel approach to analyze the effect of treatment on illness duration.

Response: Commentary: Quantile treatment effect of zinc lozenges on common cold duration: a novel approach to analyze the effect of treatment on illness duration.

Evaluation of Preventive Effect of Zinc Lozenge on Sore Throat after Placement of ProSeal Laryngeal Mask Airway: A Randomised Controlled Study

Introduction: Postoperative Sore Throat (POST) is a known complication after general anaesthesia with an endotracheal tube (14.4% to 50%) and less so with Supraglottic Airway (SGA) devices (5.8% to 34%). Various modalities and drugs can decrease POST. Zinc possesses anti-inflammatory and antioxidant properties and is utilised in oral mucositis and xerostomia. Aim: To evaluate the effect of preoperative administration of a zinc lozenge on POST after the removal of the Proseal Laryngeal Mask Airway (PLMA). Materials and Methods: In this randomised, double-blinded controlled study was conducted at the Department of Anaesthesia at Pt. BD Sharma PGIMS, Rohtak, Haryana, India, over a period of five months from August 2020 to December 2020. 100 patients aged 18-60 years of either sex belonging to American Association of Anesthesiologists (ASA) I and II undergoing elective surgery under general anaesthesia with PLMA placement were randomly allocated into two groups to receive a 40 mg zinc lozenge (Group-I) or placebo (Group-II) and were asked to chew it 30 minutes preoperatively. Patients with upper respiratory tract infections, at risk of aspiration, or with anticipated difficult intubation were excluded from the study. The incidence and severity of POST were assessed on a 4-point scale (0-3) at 30 minutes, 2, 4, and 24 hours postoperatively. The primary outcome of the study was the incidence of POST at four hours postoperatively, and the secondary outcome was the severity of POST at 30 minutes, two hours, and 24 hours postoperatively. Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) version 20.0 (IBM SPSS Statistics Inc., Chicago, Illinois, USA) Windows software programme. The Chi-square test and unpaired t-test were used for statistical analysis. Results: The mean age in Group-I was 38.6±12.32 years and in Group-II was 37.90±14.84 years (p-value 0.79). Data regarding the distribution of patients according to sex were comparable with a p-value of 0.31. There was a significantly lower incidence of POST in Group-I (zinc group) than in Group-II (placebo group) at four hours with a p-value of 0.004. Conclusion: The present study has shown that the preoperative administration of a 40 mg zinc lozenge effectively reduces the incidence and severity of POST in the postoperative period, peaking at four hours after general anaesthesia. Zinc lozenges are easy, convenient, non invasive, and successfully prevent POST.

Commentary: Quantile treatment effect of zinc lozenges on common cold duration: A novel approach to analyze the effect of treatment on illness duration.

GENERAL COMMENTARY article Front. Pharmacol., 06 April 2023Sec. Drugs Outcomes Research and Policies Volume 14 - 2023 | https://doi.org/10.3389/fphar.2023.1152305

Pitfalls in choosing data examples for methodological work: Bayesian approaches to a fixed effects meta-analysis of zinc lozenges for the common cold.

Research Synthesis MethodsEarly View LETTER TO THE EDITOR Pitfalls in choosing data examples for methodological work: Bayesian approaches to a fixed effects meta-analysis of zinc lozenges for the common cold Harri Hemilä, Corresponding Author Harri Hemilä harri.hemila@helsinki.fi orcid.org/0000-0002-4710-307X Department of Public Health, University of Helsinki, Helsinki, Finland Correspondence Harri Hemilä, Department of Public Health, University of Helsinki, POB 20, Helsinki FI-00014, Finland. Email: harri.hemila@helsinki.fiSearch for more papers by this authorElizabeth Chalker, Elizabeth Chalker orcid.org/0000-0003-1593-3770 Biological Data Science Institute, Australian National University, Canberra, AustraliaSearch for more papers by this author Harri Hemilä, Corresponding Author Harri Hemilä harri.hemila@helsinki.fi orcid.org/0000-0002-4710-307X Department of Public Health, University of Helsinki, Helsinki, Finland Correspondence Harri Hemilä, Department of Public Health, University of Helsinki, POB 20, Helsinki FI-00014, Finland. Email: harri.hemila@helsinki.fiSearch for more papers by this authorElizabeth Chalker, Elizabeth Chalker orcid.org/0000-0003-1593-3770 Biological Data Science Institute, Australian National University, Canberra, AustraliaSearch for more papers by this author First published: 12 September 2022 https://doi.org/10.1002/jrsm.1601Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

Quantile Treatment Effect of Zinc Lozenges on Common Cold Duration: A Novel Approach to Analyze the Effect of Treatment on Illness Duration.

Calculation of the difference of means is the most common approach when analyzing treatment effects on continuous outcomes. Nevertheless, it is possible that the treatment has a different effect on patients who have a lower value of the outcome compared with patients who have a greater value of the outcome. The estimation of quantile treatment effects (QTEs) allows the analysis of treatment effects over the entire distribution of a continuous outcome, such as the duration of illness or the duration of hospital stay. Furthermore, most of these outcomes have asymmetric distributions with fat tails, and censored observations are not uncommon. These features can be accounted for in the analysis of the QTE. In this paper, we use the QTE approach to analyze the effect of zinc lozenges on common cold duration. We use the data set of the Mossad (1996) trial with zinc gluconate lozenges, and three data sets of trials with zinc acetate lozenges. In the Mossad (1996) trial, zinc gluconate lozenges shortened common cold duration on average by 4.0 days (95% CI 2.3–5.7 days). However, the QTE analysis indicates that 15- to 17-day colds were shortened by 8 days, and 2-day colds by just 1 day, for the group taking zinc lozenges. Thus, the overall 4.0-day average effect of zinc gluconate lozenges in the Mossad (1996) trial is inconsistent with our QTE findings for both short and long colds. Similar results were found in our QTE analysis of the pooled data sets of the three zinc acetate lozenge trials. The average effect of 2.7 days (95% CI 1.8–3.3 days) was inconsistent with the effects on short and long colds. The QTE approach may have broad usefulness for examining treatment effects on the duration of illness and hospital stay, and on other similar outcomes.

Pre-Operative, Prophylactic Use of Oral Zinc Tablet in the Management of Post-Operative Sore Throat

Background: Postoperative sore throat (POST) is considered to be quite common complaint. Its symptoms tend to improve with time, but use of oral zinc lozenge has been shown to reduce the incidence and severity of POST. The aim of the present study was to find the efficacy of oral zinc sulfate, given 30 min preoperatively, in reducing POST, primarily caused by endotracheal intubation, till 24 hours after surgery. Method: A prospective, randomized, double-blinded, placebo-control-trial study was conducted on 80 patients, further divided into two groups of 40 patients each, between the age group of 18-60 years, of either gender, in Super Specialty Hospital, GMC Jammu, over a period of 6-months. The two groups received either dispersible zinc tablet or a placebo. The severity of POST was graded on a 4-point scale ranging from 0 to 3 and evaluation was repeated at 30 min, 2, 4, and 24 hour, postoperatively. Results: The difference in severity of sore throat was found to be statistically significant at all evaluation time intervals, except at 24 hours, which was quite lower in Zinc group. The overall incidence of POST in Zinc group was 26.3%, which was significantly higher at 50% in placebo group. Conclusion: A dose 40 mg zinc dispersible tablet, equivalent to 40 mg elemental zinc, given 30 min before surgery, effectively reduced the incidence and severity of POST. Keywords: Post Operative Sore Throat, Oral Zinc Lozenge, Endotracheal Intubation.

The effect of zinc lozenge on pain, oedema, and trismus after impacted third molar surgery: A prospective randomized, double-blinded, placebo-controlled study

The postoperative sequelae after third molar surgery include pain, swelling and trismus, Zinc acts as anti-inflammatory agent, can promote wound healing, immune system modulation, tissue repair, and significant reduction in the use of analgesics for oral pain. This study was aimed to evaluate the efficacy of oral zinc lozenge given 30 min before surgery on reducing postoperative sequelae.s: We recruited 70 patients, randomly assigned to two groups: Zinc and Control group, groups received 40mg Zinc lozenge, placebo lozenge 30 min before surgery respectively and every 6h till 72h after surgery. Third molar extraction was performed under local anesthesia. After extraction, pain, swelling, and mouth opening in both groups observed till 72h.Preoperative and postoperative measurement of visual analog scale scores for pain, edema, interincisal opening, was analyzed using Student t test or ANOVA, Chi-square or Mann-Whit­ney U test was performed for non-parametric samples. P < 0.05 was considered as statistically significant: The overall incidence of Pain in the Zinc group was 18% compared to 43% in the Control group (P = .003) Incidence of Pain, swelling, and mouth opening at different time intervals 6h, 24h, 48h and 72h were significantly (P >0.05) better in Zinc group oral zinc lozenge administered 30 minutes preoperatively can significantly reduce complications like pain, swelling, and limited mouth opening after third molar extraction.

Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial

ObjectiveTo examine a commercially available zinc acetate lozenge for treating the common cold.DesignRandomised, double-blinded, placebo-controlled trial.SettingWorking population in Finland.ParticipantsWe included men and women aged ≥18 years who usually had ≥1...

Preoperative oral zinc tablet decreases incidence of postoperative sore throat.

Background and Aims:Postoperative sore throat (POST) is very frequently reported after endotracheal intubation. Zinc lozenge has been shown to reduce POST. The aim of this study was to evaluate the effect of dispersible zinc tablet on POST.Methods:Eighty-eight patients undergoing surgery with endotracheal intubation were randomly allocated into two groups, to either receive dispersible zinc tablet 40 mg (zinc group) or placebo tablet (control group), 30 min preoperatively. Assessment for incidence and severity was performed for POST, on a 4-point scale (0–3) at 0, 30 min, 2, 4, and 24 h postoperatively. The primary outcome was incidence of POST at 4 h postoperatively. Secondary outcome was severity of POST at the 5 evaluation time points postoperatively. Mann–Whitney U test, Fisher's exact, and Chi-square test were used as applicable.Results:At 4 h, there was a significantly lower incidence of POST in zinc group (6.8%) than the control group (31.8%) with a P value of 0.003. Three patients in placebo group complained of severe POST compared to none in the zinc group. The severity of POST was significantly lower in Zinc group than Placebo group at 0 min (P = 0.003), 30 min (P = 0.002), 2 h (P < 0.001), and 4 h (P = 0.001).Conclusion:Preoperative administration of 40 mg dispersible zinc tablet effectively reduces the incidence and severity of POST in the immediate postoperative period.

Zinc deficits, mucositis, and mucosal macrophage perturbation

Mucositis is a common and therapy-limiting adverse effect of cancer treatments including radiotherapy, chemotherapy, and immunotherapy. The optimal zinc formulation, dosage, and timing of administration warrant further research as does the efficacious prevention of febrile mucositis that predisposes to febrile neutropenia. Metaanalyses concluded that zinc sulfate failed to significantly reduce the incidence or severity of chemotherapy-induced oral mucositis, whereas polaprezinc was associated with a significant reduction. Three new trials were published in 2018. The first trial found that zinc sulfate reduced the incidence and severity of chemotherapy-induced oral mucositis. The second reported that polaprezinc reduced oral mucositis in pediatric patients receiving high-dose chemotherapy for hematopoietic stem cell transplantation. The third trial demonstrated efficacy for a zinc lozenge for postoperative sore throat induced by an endotracheal intubation. Zinc deficits, dietary or induced by cancer, are common in patients with cancer. Febrile mucositis may better describe the condition linking mucositis with febrile neutropenia. Febrile mucositis disrupts treatment and may be life-threatening. A paradigm shift is needed for a more comprehensive understanding of febrile mucositis. Zinc effects on the thymic immunological network and T lymphocytes during chemoradiotherapy regimens also warrant further investigation.

Zinc lozenges efficacy in cold treatment

Zinc lozenges efficacy in cold treatment

The Effect of Zinc Lozenge on Postoperative Sore Throat: A Prospective Randomized, Double-Blinded, Placebo-Controlled Study.

Postoperative sore throat (POST) is commonly seen after endotracheal intubation, and oral zinc prevents oral mucositis associated with chemotherapy. This study is designed to evaluate the effects of administration of zinc lozenges on POST. Seventy-nine patients undergoing low- or moderate-risk surgery with endotracheal intubation were randomly assigned into 2 groups: Control group received placebo and zinc group received 40-mg zinc lozenges 30 minutes preoperatively. Patients were assessed for incidence and severity (4-point scale, 0-3) of POST at 0, 2, 4, and 24 hours postoperatively. The primary outcome was incidence of POST at 4 hours after surgery. The secondary outcomes were the incidence of POST at 0, 2, and 24 hours and the severity of POST. At 4 hours, there was a significantly lower incidence of POST in the zinc group, 7%, than the control group, 29% (P = .046). The incidence of POST at 0 hour was 0% in zinc group and 24% in control group (P = .004). The highest incidence of POST occurred at the second hour after surgery, with the rate of 10% in the zinc group and 34% in the control group (P = .0495). The incidence of POST at 24 hours was 13% in zinc group and 24% in control group (not significant). The severity of POST was significantly lower in the zinc group for mild (P = .003) and moderate (P = .004) POST. The administration of a single dose of 40-mg zinc lozenge 30 minutes preoperatively is effective to reduce both incidence of POST in the first 4 hours and severity of mild and moderate POST in the immediate postoperative period.

Indirect determination of zinc by thiol complexation and iodine coulometric titration with photocell detection

We have extended the capabilities of iodine coulometry for the determination of ionic zinc through its complexation with cysteine and subsequent titration of the thiol. The titration endpoint times of cysteine with zinc are proportionally longer as compared to cysteine itself. A homebuilt constant-current coulometer is employed for this method development. The instrument is composed of a constant-current source connected to nonisolated platinum electrodes contained in a 150-mL beaker (the coulometric cell) that sits on a photocell mounted in a styrofoam lid on top of a magnetic stirrer. Photometric endpoint detection is facilitated by connecting the photocell detector to an operational amplifier circuit; its output, recorded on a multifunctional chemical analysis system, resembled a sigmoidal curve. The titration conditions are optimized in terms of pH, temperature, stirring rate, and cysteine-to-zinc concentration ratios. Calibration curves generated as time versus increasing zinc concentrations in the presence of a constant cysteine concentration are used to determine zinc content in dietary supplements. The limit of detection is 5.5×10−5M Zn and the limit of quantification is 6.2×10−5M Zn. Percent relative standard deviations are at 4%. The recoveries of zinc from liquid zinc, enhanced zinc lozenges, and zinc tablets generally range from 80 to 120%. Titration of ascorbic acid and then zinc in the same solution is successfully performed with recoveries greater than 95% for both analytes. A comparison of the coulometry Zn data to atomic absorption results is also made for most samples.

Duration of the common cold and similar continuous outcomes should be analyzed on the relative scale: a case study of two zinc lozenge trials

BackgroundThe 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.MethodsIndividual 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.ResultsWhen 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.ConclusionsFor 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 relative effects of continuous outcomes directly from the original data should be implemented in standard meta-analysis programs.

Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage.

ObjectiveTo compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment and to examine the dose-dependency of the effect.DesignMeta-analysis.SettingPlacebo-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.ParticipantsSeven randomised trials with 575 participants with naturally acquired common colds.Main outcome measureDuration of the common cold.ResultsThe 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).ConclusionsProperly 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.

Zinc Acetate Lozenges May Improve the Recovery Rate of Common Cold Patients: An Individual Patient Data Meta-Analysis.

BackgroundA 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.MethodsWe 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.ResultsPatients 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.ConclusionsThe 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.

ZINC CONTENT IN BERRIES - THE IMPORTANCE FOR HUMAN HEALTH

Berries have become inevitable part of the diet of conscious men. Even though berries are not the richest source of zinc, there are agricultural practices that increase zinc content in surface soils. Being markedly involved in the human physiology and bio-chemistry, zinc is also a common component of plant metabolic pathways. A zinc defficiency occurs in plants mostly in calcareous and alkaline soils, affecting young leaves first. The toxicity and intolerence of zinc, which occur in the soils with prolonged use of fertilizers containing zinc among other elements, are greater problems than zinc deficiency. Zinc toxicity is often associated with the deficiency of magnesium, iron or manganese. In humans, zinc deficiency leads to acrodermatitis enteropathica, growth retardation, hypogonadism, depressed mental function, impaired cognitive functions and immune disorders, affecting males and females in the developing world. Serum zinc was correlated with the severity of depression and low serum zinc levels were found in depressed patients, suggesting that serum zinc could be the marker of depression. Diverse neurodegenerative processes, as Alzheimer's disease, may change the cellular zinc level, raising it to the level where zinc contributes to the progression of the disease. Zinc plays a pivotal role in few signal transduction and gene expression pathways, including that of cytokine genes. Zinc also holds a key position for multiple functions of cell metabolism, retinal development and specific retinal functions. Zinc in therapeutic dosages was effective in decreasing the incidence of infections. Zinc lozenges reduced the duration and severity of the common cold.

Zinc acetate lozenges for treating the common cold: an individual patient data meta-analysis.

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. 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. The total number of common cold patients was 199, the majority being females. Eighty percent of them fell into the age range 20-50years. One third of the patients had allergies. The one stage meta-analysis gave an overall estimate of 2.73days (95% CI 1.8, 3.3days) shorter colds by zinc acetate lozenge usage. The two stage meta-analysis gave an estimate of 2.94days (95% CI 2.1, 3.8days) reduction in common cold duration. These estimates are to be compared with the 7day 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. 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.

WITHDRAWN: Zinc for the common cold.

Background The common cold is one of the most widespread illnesses and is a leading cause of visits to the doctor and absence 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) (I2 statistic = 89%) but not the severity of common cold symptoms (MD ‐1.06, 95% CI ‐2.36 to 0.23) (P = 0.11) (I2 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, (I2 statistic = 75%). The incidence rate ratio (IRR) of developing a cold (IRR 0.64, 95% CI 0.47 to 0.88) (P = 0.006) (I2 statistic = 88%), school absence (P = 0.0003) and prescription of antibiotics (P Authors' conclusions Zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms in healthy people but some caution is needed due to the heterogeneity of the data. As the zinc lozenges formulation has been widely studied and there is a significant reduction in the duration of cold at a dose of ≥ 75 mg/day, for those considering using zinc it would be best to use it at this dose throughout the cold. Regarding prophylactic zinc supplementation, currently no firm recommendation can be made because of insufficient data. When using zinc lozenges (not as syrup or tablets) the likely benefit has to be balanced against side effects, notably a bad taste and nausea.