Treatment of naturally acquired common colds with zinc: a structured review

Zinc and SARS‑CoV‑2: A molecular modeling study of Zn interactions with RNA‑dependent RNA‑polymerase and 3C‑like proteinase enzymes

RNA‑dependent RNA‑polymerase (RdRp) and 3C‑like proteinase (3CLpro) are two main enzymes that play a key role in the replication of SARS‑CoV‑2. Zinc (Zn) has strong immunogenic properties and is known to bind to a number of proteins, modulating their activities. Zn also has a history of use in viral infection control. Thus, the present study models potential Zn binding to RdRp and the 3CLpro. Through molecular modeling, the Zn binding sites in the aforementioned two important enzymes of viral replication were found to be conserved between severe acute respiratory syndrome (SARS)‑coronavirus (CoV) and SARS‑CoV‑2. The location of these sites may influence the enzymatic activity of 3CLpro and RdRp in coronavirus disease 2019 (COVID‑19). Since Zn has established immune health benefits, is readily available, non‑expensive and a safe food supplement, with the comparisons presented here between SARS‑CoV and COVID‑19, the present study proposes that Zn could help ameliorate the disease process of COVID‑19 infection.

Myth Busters: Dietary Supplements and COVID-19

News and social media platforms have implicated dietary supplements in the treatment and prevention of coronavirus disease 2019 (COVID-19). During this pandemic when information quickly evolves in the presence of contradicting messages and misinformation, the role of the pharmacist is essential. Here, we review theoretical mechanisms and evidence related to efficacy and safety of select supplements in the setting of COVID-19, including vitamin C, vitamin D, zinc, elderberry, and silver. Evidence evaluating these supplements in COVID-19 patients is lacking, and providers and patients should not rely on dietary supplements to prevent or treat COVID-19. Rather, reference to evidence-based guidelines should guide treatment decisions.

Pediatric Integrative Medicine

The practice of pediatrics from an integrative framework is based on physician-patient relationship, informed by evidence, and approaches the health of children and their families from a broad perspective. This article reviews the basic principles of integrative pediatrics and summarizes data and integrative approaches to common pediatric conditions seen in the primary care setting.

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

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.

Demographic factors associated with dietary supplement prescriptions filled by United States Military Service Members 2005-2013

BACKGROUND

Dietary supplements (DSs) can be purchased over-the-counter but may also be prescribed by medical personnel for specific therapeutic reasons. Few studies have examined this latter source of DSs despite the fact that 79% of physicians and 82% of nurses have recommended DSs to their patients. This investigation examined demographic factors associated with temporal trends in oral DS prescriptions filled by all United States (US) service members (SMs) from 2005 to 2013 (n = 1,427,080 ± 22,139, mean ± standard deviation per year).

METHODS

The Food and Drug Administration National Drug Code database and the formularies of the US Defense Health Agency's Pharmacoeconomic Center were queried to identify DSs available to SMs. The number of these DS prescriptions filled by all SMs from 2005 through 2013 was then obtained from the US Department of Defense Pharmacy Data Transaction System. Data were grouped by American Hospital Formulary System (AHFS) pharmacologic-therapeutic classifications and examined over time. Denominators (number of SMs each year) were obtained from the Defense Health Agency.

RESULTS

Major findings included 1) generally greater prevalence of prescriptions filled by women and older SMs for most AHFS categories; 2) a temporal decline in total prescriptions filled by Marine Corps personnel accounted for by a decline in the prevalence of zinc preparations filled by younger male Marines; 3) a temporal decline in the prevalence of iron preparations filled by women; 4) a temporal increase in the prevalence of prescriptions for replacement preparations filled by women accounted for largely by more prescriptions for calcium compounds; and 5) a temporal decline in the prevalence of prescriptions filled for cathartics/laxatives in older SMs accounted for largely by a decline in prescriptions for sodium/potassium compounds.

CONCLUSIONS

These temporal trends may be associated with the greater health care utilization of women and older SMs as well as the perceptions of prescribers and/or patients on appropriate roles of these substances in medicine and public health.

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

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.

Temporal trends in dietary supplement prescriptions of United States military service members suggest a decrease in pyridoxine and increase in vitamin D supplements from 2005 to 2013

Dietary supplements (DSs) can be obtained over-the-counter but can also be prescribed by health-care providers for therapeutic reasons. Few studies have documented this later source despite the fact that 79% of physicians and 82% of nurses have recommended DSs to patients. This investigation assessed prevalence and temporal trends in oral DS prescriptions filled by all United States service members (SMs) from 2005 to 2013 (n = 1 427 080 ± 22 139, mean ± standard deviation (SD)/y). We hypothesize that there would be temporal variations in specific types of DSs. Data obtained from Department of Defense Pharmacy Data Transaction System were grouped by American Hospital Formulary System pharmacologic-therapeutic classifications and prevalence examined over time. About 11% of SMs filled one or more DS prescriptions of 235 180 ± 4926 (mean ± SD) prescriptions/y over the 9-year period. Curve-fitting techniques indicated significant linear declines over time for multivitamins (P = .004), iron preparations (P < .001), antacids (P < .001), and vitamin B and B complex vitamins (P < .001). There were significant quadratic trends indicating a rise in early years followed by a leveling off in later years for replacement preparations (P < .001) and vitamin C (P < .001). There were significant quadratic trends (P < .001) for vitamin E indicating a decline in early years and leveling off in later years, and vitamin D indicating little change in early years followed by a large rise subsequently (P < .001). This study identified temporal trends in specific DS categories that may be associated with changing perceptions of prescribers and/or patients of the appropriate roles of DSs in medicine and public health.

Detection of respiratory viruses by real-time polymerase chain reaction in outpatients with acute respiratory infection

Viruses are the major contributors to the morbidity and mortality of upper and lower acute respiratory infections (ARIs) for all age groups. The aim of this study was to determine the frequencies for a large range of respiratory viruses using a sensitive molecular detection technique in specimens from outpatients of all ages with ARIs. Nasopharyngeal aspirates were obtained from 162 individuals between August 2007-August 2009. Twenty-three pathogenic respiratory agents, 18 respiratory viruses and five bacteria were investigated using multiplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) and indirect immunofluorescence assay (IIF). Through IIF, 33 (20.4%) specimens with respiratory virus were recognised, with influenza virus representing over half of the positive samples. Through a multiplex real-time RT-PCR assay, 88 (54.3%) positive samples were detected; the most prevalent respiratory viral pathogens were influenza, human rhinovirus and respiratory syncytial virus (RSV). Six cases of viral co-detection were observed, mainly involving RSV. The use of multiplex real-time RT-PCR increased the viral detection by 33.9% and revealed a larger number of respiratory viruses implicated in ARI cases, including the most recently described respiratory viruses [human bocavirus, human metapneumovirus, influenza A (H1N1) pdm09 virus, human coronavirus (HCoV) NL63 and HCoV HKU1].

WITHDRAWN: Zinc for the common cold

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 due to concerns raised via the feedback mechanism regarding the calculation and analysis of data in the review in April 2015. Whilst it is not unusual for reviews to be withdrawn, the editorial group took the view that it would be better to take a cautious approach and explore the source and calculation of data used in the analysis in more detail, rather than keep the review on the Cochrane Database of Systematic Reviews for the time being.

The editorial group responsible for this previously published document have withdrawn it from publication.

Management of upper respiratory tract infections in children

Upper respiratory tract infection (URTI) occurs commonly in both children and adults and is a major cause of mild morbidity. It has a high cost to society, being responsible for absenteeism from school and work and unnecessary medical care, and is occasionally associated with serious sequelae. URTIs are usually caused by several families of virus; these are the rhinovirus, coronavirus, parainfluenza, respiratory syncytial virus (RSV), adenovirus, human metapneumovirus, influenza, enterovirus and the recently discovered bocavirus. This review will mainly focus on the rhinovirus, where significant advances have been made in understanding the epidemiology, natural history and relationship with other pathogens.

Effect of glucosamine conjugation to zinc(II) complexes of a bis-pyrazole ligand: syntheses, characterization and anticancer activity

The bis(3,5-dimethyl-1H- pyrazol-1yl)acetic acid (bdmpza) ligand was conjugated with tert-butyl-N-(2-aminoethyl) carbonate, methyl-2-amino-4-(methylthio)butanoate and 1,3,4,6-tetra-O-acetyl-β-d-glucosamine hydrochloride via amide coupling method to form three ligands L1-L3 which were then reacted with Zn(II) salts to form four zinc complexes (1-4). The complexes were characterized by (1)H NMR, (13)C NMR, electrospray ionization mass spectrometry (ESI-MS), FT-IR, CHN analyses. Complexes 1, 2 and 4 were also characterized by single crystal X-ray diffraction. It was found that Zn(II) salts could selectively remove the acetyl group from anomeric position leaving everything else intact. The cytotoxicity studies of the ligand and the complexes showed that the conjugation to acetylated glucosamine enhances cytotoxic ability although the complexes become more hydrophilic. Cytotoxicity studies in human breast adenocarcinoma (MCF-7), human cervical cancer (HeLa WT) and human lung adenocarcinoma (A549) showed that the acetylated glucosamine conjugation to the bis-pyrazole ligated Zn(II) complex led to 2-4 fold increase in cytotoxicity (IC50 values ca. 57-80μM) against HeLa WT and MCF-7 cell lines. The Zn(II) complex bearing the acetylated glucosamine inhibits the cell cycle in the G2/M phase of MCF-7 cell line. ICP-MS data shows more accumulation of Zn(II) inside the cell upon use of complex 4 as compared to Zn(II) salts or the other presented complexes. Further studies suggest that the mitochondrial transmembrane potential changes in the presence of complex 4 and caspase-7 is activated by Zn(II) salts but the activation is much more by complex 4 and hence there is apoptosis and dose dependent chromatin condensation/nuclear fragmentation as observed by microscopy.

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 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) and prescription of antibiotics (P < 0.00001) was lower in the zinc group. Overall adverse events (OR 1.58, 95% CI 1.19 to 2.09) (P = 0.002), bad taste (OR 2.31, 95% CI 1.71 to 3.11) (P < 0.00001) and nausea (OR 2.15, 95% CI 1.44 to 3.23) (P = 0.002) were higher in the zinc group. The very high heterogeneity means that the averaged estimates must be viewed with caution.

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.

Treating cough and cold: Guidance for caregivers of children and youth

Despite the widespread use of over-the-counter (OTC) cough and cold medications (CCMs), the effectiveness of most CCMs has not been proven in children. A meta-analysis summarizing trials using OTC CCMs for viral-induced cough found no evidence for or against the use of OTC medicines in both paediatric and adult populations when cough frequency and severity, as well as physician assessments, were compared. Furthermore, North American data suggest that OTC CCMs may be associated with medication errors and adverse events, resulting in visits to emergency departments and even leading to death. The present article provides information on current evidence for cough and cold therapies, including fluid intake, humidified air, antihistamines, echinacea, zinc, honey and vitamin C, for caregivers of children and youth.

Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Results of randomized controlled trials evaluating zinc for the treatment of the common cold are conflicting. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of zinc for such use.

METHODS

We searched electronic databases and other sources for studies published through to Sept. 30, 2011. We included all randomized controlled trials comparing orally administered zinc with placebo or no treatment. Assessment for study inclusion, data extraction and risk-of-bias analyses were performed in duplicate. We conducted meta-analyses using a random-effects model.

RESULTS

We included 17 trials involving a total of 2121 participants. Compared with patients given placebo, those receiving zinc had a shorter duration of cold symptoms (mean difference -1.65 days, 95% confidence interval [CI] -2.50 to -0.81); however, heterogeneity was high (I(2) = 95%). Zinc shortened the duration of cold symptoms in adults (mean difference -2.63, 95% CI -3.69 to -1.58), but no significant effect was seen among children (mean difference -0.26, 95% CI -0.78 to 0.25). Heterogeneity remained high in all subgroup analyses, including by age, dose of ionized zinc and zinc formulation. The occurrence of any adverse event (risk ratio [RR] 1.24, 95% CI 1.05 to 1.46), bad taste (RR 1.65, 95% CI 1.27 to 2.16) and nausea (RR 1.64, 95% CI 1.19 to 2.27) were more common in the zinc group than in the placebo group.

INTERPRETATION

The results of our meta-analysis showed that oral zinc formulations may shorten the duration of symptoms of the common cold. However, large high-quality trials are needed before definitive recommendations for clinical practice can be made. Adverse effects were common and should be the point of future study, because a good safety and tolerance profile is essential when treating this generally mild illness.

Zinc lozenges may shorten the duration of colds: a systematic review

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.

Complementary and alternative medicine for pain: an evidence-based review

Pain is one of the most prevalent conditions for which patients seek medical attention. Additionally, the number of patients who utilize complementary and alternative medicine as a treatment of pain either in lieu of, or concurrent with, standard conventional treatments continues to grow. While research into the mechanisms, side effect profiles, and efficacies of these alternative therapies has increased in recent years, much more remains unknown and untested. Herein, we review the literature on complementary and alternative medicine for pain, with particular emphasis on evidence-based assessments pertinent to the most common alternative therapies, including acupuncture, herbal therapy, massage therapy, hypnosis, tai chi, and biofeedback.

Autologous blood therapy for common cold--a randomized, double-blind, placebo-controlled trial

BACKGROUND

In Germany autologous blood therapy (ABT) is a widespread therapy for infectious diseases in complementary medicine. Clinical data for its use for common cold is lacking.

METHODS

In a double-blind randomized controlled trial 139 patients with common cold were enrolled either to ABT (gluteal intramuscular reinjection of venous blood three times a week) or to placebo (sterile sodium chloride solution). Main criterion was time period of illness after initiation of treatment, measured by a modified symptom diary adapted from Jackson.

RESULTS

58 and 56 patients completed therapy. In both groups illness duration was 7 days (5.0-10.0 for verum and 5.25-9.0 for placebo).

CONCLUSIONS

This trial found no effect of ABT as treatment for common cold. Because of a rather highly selected patient sample another RCT on this topic is reasonable. Further research to analyse the effect of other doses or of autologous blood therapy in addition to homeopathic preparations or vitamin preparations is needed.

Zinc lozenges as cure for the common cold--a review and hypothesis

A 7-day reduction in duration of common colds was shown by Eby et al. in 1984 using 23mg zinc gluconate throat lozenges. Over the following 25years, 14 double-blind, placebo-controlled, randomized clinical trials produced widely differing results with about one-half showing success and the remainder showing failure. Positively charged, ionic zinc (iZn), but not bound zinc, is strongly astringent, antirhinoviral, increases interferon-gamma (IFN-gamma) 10-fold, inhibits intercellular adhesion molecule-1 (ICAM-1) and inhibits the release of vasoactive ingredients from mast cell granules. Solution equilibrium chemistry analytical techniques showed lozenge iZn fraction varying from 0% to 100% of total lozenge zinc between trials, with zinc acetate (ZA) releasing 100% iZn, zinc gluconate (ZG) releasing 72% iZn and other zinc compounds releasing much less or none at physiologic pH 7.4. Since only iZn has in vitro benefits, iZn variations are hypothesized to have produced the widely varying clinical results. In support of the iZn hypothesis, lozenge iZn and total daily iZn in trials were found highly correlated with reductions in common cold durations with statistical significance for mean duration (P<0.001) and median duration (P<0.004), while total zinc (iZn plus bound) showed no correlation with changes in duration. Duration reductions (mean 0 days, median 0.43 days) for multi-ligand ZG and ZA lozenges differed significantly from duration reductions (mean 3.37 days, median 2.9 days) for single ligand ZA and ZG lozenges (P<0.001) showing that additive ligands as flavor-masks damaged or eliminated efficacy. Five of 6 trials with lozenges whose zinc compositions had a first stability constant of 1.7 or less succeeded, while only 2 of 9 trials of lozenges with higher stability succeeded (P<0.02). From the strong, multiple statistical relationships found, it is inferred that iZn is the active ingredient in zinc lozenges for colds, as it is in vitro against rhinoviruses, and that solution chemistry analytical techniques used at physiological pH are correct means for lozenge iZn analysis. Zinc lozenges slowly dissolving in the mouth over a 20-30 min period releasing adequate iZn (18 mg) used each 2h are hypothesized to shorten common colds by 6-7 days, which is a cure for the common cold. Due to inadequate lozenge iZn very few of more than 40 different brands of zinc lozenges on the US market are expected to have any effect on the duration or severity of common colds.