As of 9 June 2020, indirect evidence from other types of viral respiratory infections
suggests that zinc may potentially reduce the risk, duration and severity of SARS-CoV-2
infections; particularly for populations at risk of zinc deficiency. Notably, people
with chronic disease co-morbidities and older adults are at risk of lower zinc status.
Pending the results of SARS-CoV-2 clinical trials, clinicians might consider assessing
zinc status as part of a SARS-CoV-2 clinical work-up to determine if short-term zinc
supplementation, either orally or intravenously is indicated for those with low or
borderline low results, low dietary intake and/or increased needs.
Zinc may potentially reduce the risk of SARS-CoV-2 infections and shorten the duration
and severity of illness, including recovery from stroke, through several mechanisms.
Indirect evidence from systematic reviews have found zinc supplementation is effective
for the prevention of acute respiratory infections in young children and zinc lozenges
may reduce the duration of the common cold in adults. Safety concerns associated with
high doses or prolonged intake of zinc include anosmia (loss of smell) and copper
As of the 9 June 2020, the preliminary findings of a rapid review of zinc for the
prevention or treatment of SARS-CoV-2 and other viral respiratory tract infections
included 122 randomised controlled trials (87 were published in English and 35 in
Chinese). Only four were specific to SARS-CoV-2, and all are ongoing. Other ongoing
SARS-CoV-2 trials are investigating the potential role of zinc as an agonist (additive)
to hydroxychloroquine against placebo controls or in combination with other nutraceuticals,
most commonly Vitamin C and D. No other direct evidence pertaining to SARS-CoV-2 nor
other coronavirus infections was identified. A detailed analysis of the indirect evidence,
including meta-analyses, is underway.
Pending any definitive evidence, clinicians might consider assessing the zinc status
of people with chronic disease co-morbidities and older adults as part of a SARS-CoV-2
clinical work-up, as both groups have a higher risk of zinc deficiency/insufficiency
and poorer outcomes from SARS-CoV-2. Supplementation might be indicated for those
with low or borderline low results, low dietary intake and/or increased needs.
The global COVID-19 pandemic has prompted an urgent search for pharmaceutical and
traditional, complementary and integrative medicine (TCIM) interventions. Data from
all countries indicate that the case fatality and morbidity rates from SARS-CoV-2
increases with age and for those with non-communicable chronic disease co-morbidities.
[, , , ] Notably, zinc deficiency/insufficiency is prevalent in populations
aged over 71 years [, , , , ], in people with chronic diseases [,
, ] including diabetes [10,12,13], and cardiovascular diseases [10,12] and
hospitalised patients following stroke  – see Box 1
Populations at risk of zinc deficiency.
Insufficient dietary intake of zinc
Limited access to animal foods [, , ]
Consume plant based diets high in cereals, starchy roots, tubers and legumes (containing
phytic acid which may reduce zinc bioavailability [17,18]
Infants weaned from breast milk
Hospitalisation following stoke 
People with increased biological need
Pregnant and breastfeeding women [19,20]
Early post-natal infants [20,21]
Chronic diseases (e.g. chronic obstructive pulmonary diseases, asthma, anaemia, renal
disease, inflammatory bowel and other chronic gastrointestinal diseases, HIV, Alzheimer’s
disease, rheumatoid arthritis) [22,23]
Alcohol abuse 
Alt-text: Box 1
Zinc is widely available for self-prescribed use and is a common naturopathic medicine
used for a variety of clinical indications, including the prevention and treatment
of viral respiratory infections, tissue repair and supporting healthy immune system
function . Zinc plays an important role in immune function, wound healing, insulin
and blood pressure regulation, and the regulation of gene expression . Zinc is
formulated as a stand-alone nutraceutical or as a combination product containing other
minerals, vitamins and/or herbs. Most zinc supplements are administered orally either
in single or divided daily doses, in the form of a lozenge, tablet, capsule, liquid
or syrup. Some products are formulated for intramuscular or intravenous administration.
Zinc supplementation is not without potential safety concerns, that includes anosmia
 and copper deficiency associated with higher doses and prolonged intake .
The daily recommended dietary intake (RDI) of elemental zinc is around 2 mg for infants
up to 6 months of age, and gradually increases to 11 mg for males, and 8 mg per day
for females older than 13 years . Tolerable upper limits for zinc are estimated
to be 7 mg for children aged 1–3 years of age, increasing up to 25 mg for adults and
females of any age who are pregnant or lactating. The no observed adverse effect level
(NOAEL) for adults is around 50 mg/day .
Over 17 % of the global population is estimated to be zinc deficient , and 20
% of national diets contain insufficient zinc to meet minimum health requirements
[31,32]. Deficiency is highest in South-East Asia, Sub-Saharan and Central and South
American regions, however, marginal deficiencies are also prevalent in developed regions
Assessment of zinc status is notoriously difficult due to absence of sensitive and
precise biochemical indicators. The most reliable methods involve combining a clinical
assessment with laboratory tests assessing tissue concentrations of zinc in plasma
or hair . Clinical manifestations of mild-moderate zinc deficiency include recurrent
infections, slow tissue repair, rough skin, mental lethargy, irritability, headaches
and reduced lean body mass . Assessment of dietary zinc with validated food frequency
instruments may help identify dietary insufficiency  however zinc status is still
likely to be underestimated due to individual physiological characteristics .
For instance, whilst zinc insufficiency/deficiency is known to diminish antibody and
cell-mediated immunity in humans that in turn increases the risk of infections, this
may only become apparent upon immune system provocation [38,39].
Through several mechanisms, zinc has the potential to reduce the risk of viral respiratory
tract infections, including SARS-CoV-2, and shorten the duration and severity of illness.
The authors of a recent non-systematic narrative review of the underlying mechanisms
postulate that along with its direct antiviral properties, zinc has the potential
to reduce inflammation, improve mucocillary clearance, prevent of ventilator-induced
lung injury, and modulate antiviral immunity  (Fig. 1
The proposed protective mechanisms of zinc in Covid-19. From “Zinc and respiratory
tract infections: Perspectives for COVID‑19 (Review)” by Skalny, A.V., Rink, L., Ajsuvakova
O. et al. 2020 in the International Journal of Molecular Medicine; Volume 46, Issue
1, page 21. Copyright Spandidos Publications .
In vitro studies have demonstrated that zinc can inhibit the enzymatic activity and
replication of SARS-CoV RNA polymerase and may inhibit angiotensin‑converting enzyme
2 (ACE2) activity [40,42,43]. The antiviral effects of zinc are also hypothesised
to potentiate the therapeutic effects of chloroquine , as chloroquine acts as
a zinc ionophore increasing Zn2+ influx into the cell . Zinc may also modify the
host’s response to an infection as it is an essential co-factor element with a broad
range of functions in the body. Zinc has an essential role in immune and airways function,
wound healing and tissue repair that in turn, may delay or prevent recovery from viral
respiratory illnesses [, , , , , , ]. Other consequences
of zinc deficiency include an increased risk of vitamin A deficiency that is also
critical for immune function, due to carrier proteins and activation enzymes being
dependant on sufficient zinc status .
The potential role of zinc as an adjuvant therapy for SARS-CoV-2 may be broader than
just antiviral and/or immunological support. Zinc also plays a complex role in haemostatic
modulation acting as an effector of coagulation, anticoagulation and fibrinolysis
[53,54]. Zinc is also essential for neurological function and normalisation of zinc
intake has been shown to improve neurological recovery following stroke .
The effectiveness of zinc in preventing or treating SARS-CoV-2 infections is yet to
be systematically evaluated and, along with other nutritional supplements, was not
mentioned in a recent narrative review of TCIM for the treatment of coronavirus disease
2019 (COVID-19) . The findings of systematic reviews of related populations are
promising; however, the reviews are limited by population, intervention, or are out
of date [, , ].
A 2016 Cochrane review of six RCTs concluded zinc supplementation was effective for
the prevention of pneumonia in children aged two to 59 months . Unlike an earlier
review in 2000 of seven RCTs with adult participants and one RCT with children ,
an updated 2011 systematic review of 13 RCTs found a dose-dependent effect of zinc
lozenges compared to placebo controls for reduced duration of common colds in adults
. Daily dosages less than 75 mg of zinc had no significant effect on duration
of colds, however, daily dosage over 75 mg reduced the duration of colds by 42 % (95
% CI: 35 %–48 %). In a subsequent 2017 systematic review of seven RCTs of zinc lozenges
with a daily dose >75 mg, a smaller reduction of 33 % (95 % CI 21 %–45 %) in the duration
of common colds was found . No differences in duration were found for daily doses
of 192−207 mg compared to doses of 80−92 mg.
Other formats of zinc for preventing or treating upper respiratory infections were
examined in three Cochrane systematic reviews, however, all were withdrawn [56,62,63].
A protocol for the systematic review of zinc for prevention and treatment of common
colds was withdrawn in 2019 due to non-completion within the editorial time-frame
The primary objective of this rapid review was to assess the effects of zinc on the
incidence, duration and severity of acute upper or lower respiratory tract infections
caused by SARS-CoV-2 infection in people of any age and of any zinc status when used
as a preventive supplement or as a therapy.
The secondary objectives are to assess the effects of zinc on the incidence, duration
and severity of acute upper or lower respiratory tract infections
caused by other coronavirus species, with a focus on SARS-CoV and MERS-CoV infections;
predominantly caused by viruses; and
in subgroups of populations at risk of zinc insufficiency/deficiency and those with
a higher risk of severe acute respiratory syndrome (SARS) caused by SARS-CoV-2 infection.
A protocol for this rapid review outlining the methods in detail, including the methodological
constraints employed to facilitate a timely answer to the review questions, was registered
on 24 April 2020 with PROSPERO: CRD42020182044 .
Rapid review method constraints included not systematically searching the bibliographies
of included articles, and jointly screening (SA, GY, JZG, JH), only 30 title/abstracts
and 5 full-text articles for calibration and consistency, after which only one reviewer
(SA,GY, JZG JH) screened each article. Similarly, only three studies and their outcomes
were jointly assessed (SA, GY JH) for calibration and consistency using the Cochrane
RoB 2.0 tool [66,67] and a piloted rubric. Study characteristics and data were extracted
into a piloted electronic spreadsheet, after which only one reviewer (SA, GY, JH)
assessed RoB and extracted data for each study.
Primary studies included were randomized controlled trials (RCTs) and quasi-randomised
controlled trials. There were no date nor language restrictions, however, studies
published in languages other than English or Chinese are yet to be translated.
Included were people of any age, gender and zinc status in any setting who are 1)
at risk of contracting an acute upper or lower viral respiratory tract infection,
including healthy populations, 2) have a confirmed SARS-CoV-2 or other respiratory
infection caused by a coronavirus species, including SARS-CoV and MERS-CoV, and/or
3) have either a laboratory confirmed viral respiratory tract infection (any virus)
or an acute respiratory tract infection where the cause is most likely viral such
as the common cold, non-seasonal rhino-sinusitis, laryngitis, flu-like illness, healthy
people with acute bronchitis, or young children with pneumonia.
Included were any zinc conjugates, such as salts or amino-chelates as a single ingredient,
in any form (e.g. tablet, syrup, lozenge, gel, spray, liquid), dose and duration,
administered via oral, intranasal, sublingual, transdermal, intramuscular or intravenous
Excluded were systematic reviews, non-randomised studies of interventions and studies
without a concurrent control, such as case series and case reports.
Excluded were people with respiratory tract infections or other upper/lower respiratory
illnesses when the cause was confirmed not to be a viral infection, or a non-viral
cause is common.
Excluded were co-interventions and zinc administered alongside other nutraceuticals,
herbs or pharmaceuticals unless both the intervention and control groups received
the co-intervention. The exception were co-ingredients with the primary purpose to
facilitate absorption (e.g. vitamin B12) or cellular retention (e.g. vitamin B6 or
magnesium) of zinc.
The following databases were searched from inception: PubMed on the 8 May 2020, selected
EBSCO host databases (Academic Search Complete, Allied and Complementary Medicine
Database (AMED), Alt Health Watch, CINAHL Plus with Full Text, Health Source, and
PsycINFO), Embase and Cochrane CENTRAL on the 27 April 2020, and the China Knowledge
Resource Integrated Database (CNKI) on 29 April 2020.
Additionally, the following clinical trials registries were searched on for SARS-CoV-2
infections only. The U.S. National Library of Medicine Register of Clinical Trials
(ClinicalTrials.gov), International Standard Randomized Controlled Trial Number Register
(ISRCTN) and World Health Organization International Clinical Trials Registry Platform
(WHO ICTRP) were searched on 5 May 2020. The Chinese Clinical Trial Registry was searched
on 29 April 2020.
Search terms (example)
PubMed - Boolean/phrase
(Coronaviridae[mh] OR Coronavir* OR nCov OR covid OR Coronaviridae Infections[mh]
OR Middle East Respiratory Syndrome Coronavirus[mh] OR "Middle East Respiratory Syndrome"
OR MERS OR "Severe Acute Respiratory Syndrome" OR “Severe acute respiratory syndrome-related
coronavirus” OR “Severe Acute Respiratory failure” OR “Acute febrile respiratory syndrome”
OR SARS OR Respiratory Tract Infections[mh] OR “Lower respiratory infection” OR “viral
respiratory” OR pneumonia OR “flu -like illness” OR bronchitis OR “Common cold” OR
Rhinitis OR laryngitis OR “Respiratory Infections” OR “Infections, respiratory” OR
“Infections, Respiratory Tract” OR “Infections, Upper Respiratory” OR “Upper Respiratory
Tract” OR “Infections, Lower Respiratory Infections” OR “Lower Respiratory Infections”
OR “Lung Inflammation” OR “Lobar Pneumonia” OR “Lobar Pneumonitis” OR “Pulmonary Inflammation”)
AND (Zinc[mh] OR zinc OR zn) AND (randomized controlled trial[pt] OR controlled clinical
trial [pt] OR randomized [tiab] OR placebo [tiab] OR drug therapy [sh] OR randomly
[tiab] OR trial [tiab] OR groups [tiab]) NOT (animals [mh] NOT humans [mh])
A total of 1625 records were retrieved from the database searches, of which 1182 records
remained after duplicates were removed. A further 981 records were excluded at title
and abstract screening, and 80 following full-text screening (due to ineligible study
design n = 29, population n = 11 or intervention n = 32; full-text not available n = 7;
or awaiting translation n = 1), leaving 121 records reporting 122 primary studies
(86 published in English and 35 in Chinese). One study published in Spanish is pending
Four trials specific to SARS-CoV-2 were included, all of which are currently ongoing,
and the investigators have been contacted are yet to report their results. A further
15 ongoing trials were excluded as the interventions used zinc in combination with
other nutraceuticals (most commonly vitamin C and D) and/or as an agonist (additive)
to hydroxychloroquine. As such, the independent effects of zinc cannot be determined.
Of the remaining 118 published studies, none investigated zinc for prevention or treatment
of acute respiratory infections caused only by a coronavirus infection. Most of the
studies (79 %) evaluated zinc for treating or preventing upper and/or lower acute
respiratory infections in children. (Table 1
). All the studies of adult participants were for acute upper respiratory infections
i.e. the common cold (Table 1), of which 21 were naturally occurring infections and
six inoculated the participants with human rhinovirus species.
RCTs and quasi-RCTs of zinc for acute viral respiratory infections.
Zinc for treatment only
Zinc for prevention only
Zinc for prevention and treatment
CNKI: China Knowledge Resource Integrated Database.
The prevention effect of zinc was assessed in a variety of ways, mostly as the incidence
or recurrence of respiratory infections as reported by study clinicians, the participants’
physician or other healthcare workers, parents or self-reports, hospitalisation and/or
laboratory tests. Treatment effects for severity and duration included time to symptom
resolution, fever or respiratory distress, time in hospital, viral shedding, and self
or clinician reported clinical severity.
A wide range of zinc formulations and dosages were used, including lozenges, nasal
gels and sprays, and oral zinc delivered in syrup, tablet or capsule formats. Only
one study evaluated intravenous zinc.
Most studies were conducted in community settings. The studies of children were representative
of all WHO regions, whereas most of the adult studies were conducted in the United
States (n = 19), three were in the WHO Western Pacific Region and in WHO Europe Region.
Summary of findings
Currently, there is no direct evidence to determine if zinc is effective for either
the prevention or treatment of SARS-CoV2-19. The protocols of four RCTs have been
registered and are currently recruiting. One aims to evaluate zinc on the clinical
course of SARS-CoV2-19 in non-hospitalised participants in the community. The second
will compare zinc against placebo controls for oxygen saturation in hospitalised patients
admitted with SARS-CoV2-19. The third and fourth registered trials aim to compare
the effectiveness of zinc as adjunct treatment to hydroxychloroquine, one study for
prevention and the other for treatment of SARS-CoV-2. Hydroxychloroquine is a zinc
ionophore increasing the influx of zinc ions into cells. The third and fourth trials
include participants from populations at high risk of zinc deficiency.
The first study, “Coronavirus 2019 (COVID-19) - Using Ascorbic Acid and Zinc Supplementation
(COVIDAtoZ)” (NCT04342728), plans to recruit 520 adults with a confirmed SARS-CoV-2
infection who do not require hospital admission. Based in a community setting in the
United States (US), COVIDAtoZ is a four-arm pragmatic RCT comparing zinc gluconate
only, zinc gluconate and Vitamin C, Vitamin C only, and usual care (standard prescribed
medication/supplements). The dose of zinc gluconate is 50 mg daily, taken at bedtime.
The primary outcome is the number of days required to reach a 50 % reduction in symptom
severity score (derived from a composite self-rating score of fever, cough, shortness
of breath and fatigue rated on a 0–3 scale). Secondary outcomes are time to symptom
resolution for each symptom, total symptom composite score at day 5, proportion requiring
hospitalisation, use of prescribed adjunctive medicines, and adverse events. Methodological
limitations include subjective primary outcome measures from unblinded participants,
potential uncertainty around the quality and quantity of the ingredients in the supplements
, a potentially insufficient dose of elemental zinc and that the usual care group
may use any combination of readily available prescribed medications / supplements,
including zinc or vitamin C. Strengths of the pragmatic design include a capacity
to inform ‘real-world’ decisions about any benefits and risks of additional zinc supplementation
using products that are readily available compared to usual care alone.
The second study, “High-dose intravenous zinc (HDIVZn) as adjunctive therapy in COVID-19
positive critically ill patients: A pilot randomized controlled trial” (ACTRN12620000454976),
is being conducted in a hospital setting in Australia. HDIVZn is a two-arm, double-blind
RCT comparing intravenous zinc chloride (0.5 mg/kg/d) or placebo in 250 ml saline
bags infused daily over 3−6 h for seven days. HDIVZn aims to recruit 160 patients
who are hospitalised with SARS-CoV-2 infection. The primary outcome is oxygenation.
Secondary outcomes are concerned with feasibility, including adequacy of blinding,
availability/delivery/storage of the zinc infusions and per-patient costs. Methodological
strengths include blinding and the use of an objective primary outcome measure. Limitations
include not assessing any other clinical outcomes listed in the core outcome set (COS)
for clinical trials on COVID-19 . The dose of zinc, approximately 50 % more than
the minimum daily requirement and without an intracellular transporter co-factor,
may be insufficient to effect change of the outcome measurements . Given this
is a single-centre trial located in Australia with a low incidence of SARS-CoV-2,
as of the 14th June 2020, no eligible participants had been recruited to the study;
and, according to the investigator A/Professor Ischia, “due to the low numbers of
COVID-19 infections, the trial is unlikely to reach full recruitment to achieve its
desired statistical power” .
Prevention of SARS-CoV-2 is being evaluated in a multicentre trial of 660 military
health professionals exposed to SARS-CoV-2 and located in Tunisia (NCT04377646: A
Study of Hydroxychloroquine and Zinc in the Prevention of COVID-19 Infection in Military
Healthcare Workers (COVID-Milit)). Participants will be randomized to one of three
study arms; either hydroxychloroquine and zinc, hydroxychloroquine and placebo, or
two placebo controls. In COVID-Milit, hydroxychloroquine 400 mg will be administered
at day 1 and day 2, then as a weekly dose for up to 2 months. Zinc will consist of
15 mg per day for up to two months. The primary outcome is the frequency of infection
at two months, secondary outcomes are frequency of ten symptoms and adverse events.
The low dose of zinc will provide minimum intake required for health.
The treatment of SARS-CoV-2 with either hydroxychloroquine plus zinc compared to hydroxychloroquine
alone will be evaluated in 80 hospitalised adults with confirmed SARS-CoV-2. This
study, registered on the Iranian clinical registry (IRCT20180425039414N2; The effect
of zinc on the treatment and clinical course of patients with SARS-cov2 (COVID-19)),
is being conducted at the Amin Hospital in Isfahan. Participants will be randomised
to either Hydroxychloroquine 200 mg every 12 h plus zinc 220 mg twice daily, or to
hydroxychloroquine alone during their hospital stay. Outcomes include mortality rates,
length of hospital stay and the clinical course of SARS-CoV-2 (fever, shortness of
breath, cough, blood oxygenation (SaO2) and hemodynamic parameters). The treatment
study was designed to ensure that all study participants diagnosed with SARS-CoV-2
Preliminary findings of this rapid systematic review found limited direct evidence
evaluating zinc for the prevention or treatment of SARS-CoV-2, as the results of the
four registered RCTs that were identified are pending. Once available, the findings
from the COVIDAtoZ trial that is evaluating the comparative effectiveness of zinc
supplements against vitamin C and usual care for treatment of mild to moderate symptoms
of community-based SARS-CoV2-19 infections, will be relevant to the general population
who can self-prescribe, along with a wide range of health practitioners who provide
TCIM advice. The findings from the HDIVZn trial that is evaluating the efficacy and
safety of intravenous zinc infusions for hospitalised patients may provide safer and
less expensive therapeutic options compared to pharmaceuticals currently being evaluated.
Delivery of the intervention, however, requires medical oversight that will restrict
its application to hospital settings and perhaps a few primary care settings. The
two comparative effectiveness studies will not explain the preventative or treatment
effects of zinc as a stand-alone therapy, however they will explain the potential
benefits of zinc adjunct to hydroxychloroquine in populations at high risk of zinc
deficiency , for the prevention of SARS-CoV-2 in health professionals and for
treatment of patients hospitalised due to SARS-CoV-2.
In contrast, a substantial volume of indirect clinical evidence from RCTs investigating
zinc for preventing and/or treating acute respiratory infections commonly caused by
viruses was identified. Only 20 of the 120 RCTs included in this rapid review have
previously been meta-analysed and whilst the results are promising they are limited
to infants (n = 6) , children (n = 1)  and zinc lozenges in adults (n = 13)
[, , ]. The studies identified in this rapid review therefore warrant
further in-depth appraisal and meta-analysis where possible. To facilitate the rapid
dissemination of results that are most relevant to populations at a higher risk of
morbidity and mortality from SARS-CoV-2, an analysis of the 20 RCTs of zinc for upper
respiratory tract infections in adults will be undertaken first prior to analysing
the studies involving children. Whilst the grading of the evidence will be downrated
due indirectness, in the absence of more direct evidence, the findings are clinically
relevant as an estimated 15 % of upper respiratory tract infections in adults are
caused by coronaviruses .
Along with the positive findings from the limited systematic reviews to date, the
rationale for the use of zinc in SARS-CoV-2 prevention and treatment, and possibly
rehabilitation, is supported by the known mechanistic actions of zinc as an antiviral
agent [40,42,43], and a key element for a broad range of functions in the body that
modulate immunity, respiratory tract inflammation, coagulation and neurological function
to name a few [14,, , ,, , , , , , , ,
Pending any definitive evidence, it might be reasonable for clinicians to consider
assessing the zinc status of people with chronic disease co-morbidities and older
adults as part of a SARS-CoV-2 clinical work-up, as both groups have a higher risk
of zinc deficiency/insufficiency and poorer outcomes from SARS-CoV-2. Zinc status
can be assessed by taking a diet and clinical history (see Box 1), clinical examination
and laboratory tests. Plasma zinc may be more reliable than serum zinc and whilst
hair mineral analysis is another option a timely result may not be available .
For prevention of SARS-CoV-2 and most importantly for general health, given that zinc
supplements are readily available, they may be indicated for people with low or borderline
low results, low dietary intake and/or increased needs. To optimise safety, a daily
dose lower than the tolerable upper limits (<7 mg for children aged 1–3 years up to
22 mg for those aged 15–17 years) should be used along with dietary modifications
whenever possible. In adults, doses up to the no observed adverse effect level (NOAEL)
of 50 mg/day should be considered . At this stage, it is unclear if there is any
additional benefit from supplementing zinc for the prevention of SARS-CoV-2 or other
viral respiratory infections in low risk populations nor for people with normal zinc
It is also unclear if there are any benefits from supplementing with zinc for the
treatment of SARS-CoV-2. There is limited indirect evidence from viral upper respiratory
infections that zinc lozenges with a daily dose of >75 mg of zinc may shorten the
duration of the common cold. However, there are risks with higher doses above the
NOAEL including permanent loss of smell . Therefore, a daily dose higher than
100 mg of elemental zinc in a lozenge is probably not advisable, as it is questionable
whether there are any additional therapeutic effects .
This article has not been peer-reviewed; it should not replace individual clinical
judgement. The views expressed in this rapid review are the views of the authors and
not necessarily from the host institutions. The views are not a substitute for professional