The Use of Zinc Lozenges to Treat Acute Respiratory Tract Infection
Summary For more than twenty years, clinicians have studied the efficacy of zinc lozenges in treating acute respiratory tract infections (the common cold). Study results vary significantly, as the studies have used differing zinc compounds, dosages and study designs. However, in well-designed clinical studies, the compound zinc gluconate glycine in a corn-syrup lozenge form has shown consistent efficacy in reducing the duration and severity of the common cold. Introduction
antitussives, and combination products that offer two
According to some estimates, Americans suffer from
as many as one billion colds each year (NIAID Fact
Sheet 2001). The National Center for Heath Statistics
While traditional over-the-counter medications can
estimates that in 1996, the common cold caused
improve cold symptoms, these medications have not
Americans to miss nearly 20 million days of work
been shown to reduce the length or underlying
and 22 million school days (Adams 1999). The
severity of a cold. In addition, traditional over-the-
common cold’s immense economic impact makes
counter cold medications can pose risks, in particular
prevention and treatment options of key importance.
Each year, patients make more than 25 million office
• Following an FDA warning regarding accidental
visits seeking treatment options for colds (Gonzales
overdose, several children’s cold medications
2001). Because prescription medications such as
were voluntarily withdrawn from market in 2007.
antibiotics are not effective in treating the common
• Certain over-the-counter cold remedies can be
cold (a virus), clinicians can only offer patients
misused by teenagers seeking an easy and
advice on using over-the-counter medications,
nonpharmacological therapy, and/or homeopathic
• Senior citizens are at a higher risk of side affects
Acute Respiratory Tract Infections
Acute respiratory tract infections develop after
exposure to infected secretions or to small- or large-
Along with nonpharmacological therapy such as
particle aerosols after an infected person sneezes or
drinking water, room humidification, saline gargles,
and so on, homeopathic cold remedies such as
vitamin C, Echinacea, and zinc can be used.
Once the cold virus enters the body, it moves to the
throat and binds to the intercellular adhesion receptor
The zinc gluconate glycine lozenge is a homeopathic
molecule-1 (ICAM-1). The virus then reproduces in
option that has been clinically shown to reduce the
respiratory epithelial cells and spreads throughout the
duration and severity of the common cold. These zinc
nasopharynx area (Cauwenberge 2000, Winther
lozenges have few side-affects and none of the risks
associated with traditional over-the-counter cold
The virus spreads quickly, and cold symptoms
typically begin within 12 hours following infection.
Zinc Lozenges
Patients typically experience cold symptoms for a
Zinc lozenges marketed for treating acute respiratory
week to ten days; some symptoms can linger for up
tract infections contain as the active ingredient either
Treatment Options Traditional Over-the-Counter Medications
Zinc gluconate glycine is a zinc compound that
For patients who seek over-the-counter cold
contains both zinc gluconate and the amino acid
medications, a range of products area available for
glycine. This formulation allows for an extended
the reduction of cold symptoms. These include
shelf life and a more palatable taste. In 1985, the zinc
gluconate glycine compound was patented, and it is
now marketed and distributed under the brand Cold-
Each Cold-EEZE® zinc lozenge provides 13.3 mg of
ionic zinc per lozenge. Cold-EEZE® releases positive
zinc ions into the membranes in the mouth. Up to six
lozenges may be taken per day. For adults and
Zinc acetate is used in lozenges to treat the common
children 12 years and older, this dosage can help
cold, in dietary supplements, and as an astringent in
strengthen the immune system, and is required for the
ointments or lotions. Clinical studies have not shown
development and activation of T-lymphocytes that
zinc acetate to be as effective as zinc gluconate
glycine for the reduction in length and severity of
Study Results
A wide range of clinical studies have been conducted
to analyze the effectiveness of zinc in treating the
The use of zinc lozenges in treating the common cold
common cold. (See table in Appendix for summary.)
has gained significant support from the medical
community as an intervention in rhinovirus colds.
Independent, double-blind, clinical studies of zinc
While zinc’s mechanism of action in treating the
gluconate glycine lozenges, conducted by leading
common cold is not entirely understood, there are
infectious disease specialists at both the Cleveland
Clinic and Dartmouth College, were published in the
well-respected Annals of Internal Medicine (Mossad
• Zinc lozenges may prevent the development of a
1996) and Journal of International Medicine
protein that cold viruses need to reproduce. Once
Research (Godfrey 1992). Both of these peer-
virus reproduction ceases, cold symptoms begin
reviewed, published studies support the effectiveness
of Cold-EEZE® zinc gluconate glycine lozenges in
• Zinc may attach to the proteins of critical nerve
reducing the symptoms of the common cold by
endings and to proteins at the edge of a cold
virus, interrupting nerve impulses and prohibiting
the virus from entering the body’s cells. This
In 1984, George Eby was the first to study zinc
tablets that were dissolvable in the mouth. He created
experienced by patients taking zinc lozenges.
a formula that determines the strength of the zinc
Zinc ions may be an important anti-inflammatory
lozenge called “zinc ion availability.” The study
concluded that ionic zinc notably shortened the
• Zinc salts may act to protect and stabilize the
duration of a cold and reduced the severity of its
body’s cell linings, reducing the impact of a cold
symptoms. The unflavored zinc gluconate was
unpalatable, however, which caused a high patient
dropout rate for the clinical studies (Eby 1984).
The primary cited side-affects of zinc therapy for
In 1987, after a tolerance study, double-blind placebo
colds are dysgeusia (temporary dysfunction of the
controlled trials were performed to determine the
sense of taste) and stomach upset. Using zinc
prophylactic effect of zinc gluconate lozenges on
lozenges after a meal can help reduce these side-
rhinovirus challenge. In the third study, the
therapeutic efficacy of the lozenge was tested when it
was given at the start of the cold. Patients were
Cold-EEZE®-brand Zinc Lozenges
isolated for 48 hours, and then induced with a human
Cold-EEZE®-brand zinc gluconate glycine lozenges
rhinovirus. Daily examinations were given that
have been shown in clinical studies to reduce the
included grading of colds, weighing of nasal
duration and severity of the symptoms of the
secretions, counts of tissues used, blood samples for
common cold by 42 percent. Cold symptoms include
hematological values and 24-hour urine for zinc
cough, stuffy nose, sore throat, sneezing, post-nasal
content. As a result, it was concluded that zinc
drip and hoarseness. Cold-EEZE® lozenges are most
effective when taken at the first sign of a cold.
In 1992, patients showing cold symptoms within the
In 2006, Kurugol et. al. studied a group of 200
previous two days were randomly chosen to have
school-age children using zinc sulfate syrup over a
placebo or zinc. The patients with zinc were given
period of seven months. The study group received 15
23.7 mg of zinc gluconate lozenges every two hours
mg of daily prophylactic, and 15 mg twice daily after
for 10 days or until the symptoms stopped. Each day,
the onset of a cold and until symptoms were resolved.
the patients’ symptoms were monitored. As a result,
Results of this study showed a reduction in the
zinc helped reduce the symptom severity by 1.27
number of colds, and a reduction in the number of
cold-related absences from school. There was also a
shorter duration of cold symptoms in the zinc group
In 1996, patients recruited from a health care center
versus the placebo group (Kurugal, 2006).
were admitted into the study if they showed at least 2
of 10 predetermined symptoms within 24 hours. The
In 2004, in response to a critic’s assertion that zinc
group was randomly divided into zinc and placebo.
lozenges do not deposit zinc ions in the nasal
13.3 mg of zinc gluconate were given to the patients
mucosa, a joint study (available for review but
every two hours until the symptoms disappeared. As
currently unpublished) was conducted by Retroscreen
a result, the zinc group had a shorter duration than the
Virology (University of London) and Synergy
placebo group (4.4 days vs. 7.6 days). In addition,
Research, Inc. Results of this phase II, single-center,
nasal drainage, sore throat, cough, headache, and
clinical trial indicate a statistically significant
increase in zinc levels in the nasopharynx
immediately after the oral administration of a Cold-
In a review of cases from January 1998 to August
EEZE® lozenge. This suggests that the oral
2001, 496 patient cases were analyzed regarding the
administration of Cold-EEZE® results in increased
use of zinc gluconate glycine lozenges in school-age
zinc levels in the nasopharynx and is useful as a
children. One lozenge (13.3 mg) was giving daily as
therapeutic agent in the prevention of rhinovirus
a prophylactic to 119 patients in the zinc group.
Findings included a significant reduction in the
Another recent clinical trial set out to determine if zinc
median number of colds in the zinc group.
can be detected in the nasopharynx after
administration of zinc gluconate lozenges containing
One study involving 48 adults found zinc acetate
13.3 mg of ionic zinc, using healthy human adult
lozenges (12.8 mg zinc per lozenge) taken every two
to three hours while the patient is awake reduced the duration of cold symptoms compared to placebo (4.5
• The mean change in zinc at the second sampling
(using the time of administration of the lozenge as
One placebo-controlled, seven-day study observed 65
baseline) was statistically significant (p=0.00210)
individuals who took either a loading dose of 46 mg
based on the Wilcoxon rank sum test of 32
zinc (two zinc gluconate lozenges) followed by 23
mg zinc (one lozenge) or placebo every wakeful hour until symptoms were absent for six hours. After
• Twenty-five of thirty-two subjects (78%) showed
seven days, 86% of the zinc group were symptom-
an increase of zinc in their nasal mucosa at the
free compared to 46% of the placebo group
• The mean change in zinc at the second sampling
In a seven month, phase IV trial, 134 school children
time (using the time of administration of the
were given 13.3 mg zinc (one zinc gluconate
lozenge as Baseline) was statistically significant
lozenge) daily as a preventative and 53.2 mg zinc
(p=0.00333) based on the Wilcoxon rank sum test
(four zinc gluconate lozenges) daily at cold onset
until symptoms resolved. Previously collected data
• After the oral administration of one lozenge, there
was used as a control. Average cold duration days 9.0
was a statistically significant level of zinc in the
+/- 3.5 days for the control group (McElroy 2004).
• A statistical analysis was performed to determine
common cold. This statement is unsupported, as the
how long zinc persisted in the nasal mucosa. Fifty-
authors of this report did not consider study factors
six percent (56%) of subjects returned to their
that have a significant impact on results, such as:
baseline measurement, or below their baseline
measurement, of zinc at the third and final nasal
swab (performed on subjects between 10 and 180
• Variance in endpoints or severity scoring
• Forty-four percent (44%) of patients continued to
show an elevated level of zinc, represented by an
increase over their baseline measurement, at the
Furthermore, the authors defined a specific set of eleven criteria to select the published papers for
their source material. This does not necessarily
Studies with Inconclusive or Negative Results
mean that one or more of their criteria were not
While published studies exist that show inconclusive
performed in the unselected studies. A review of
or negative results regarding the use of zinc in
protocols and study reports would have provided a
treating the common cold, these studies each contain
more accurate understanding, as the description of
one or more of the following flaws in design:
specific study methodology does not necessarily get
reported in published papers. There was no review
• Inadequate zinc dosing (4.5 mg, 10 mg)
by these authors of per-protocol compliance.
• Unavailable zinc ions due to chelating effect
of pharmaceutical binders and sweeteners
For example, the report by Caruso et. al. included a
(sorbitol, manitol, citric acid, ascorbic acid)
1998 JAMA study by Macknin et. al. (referenced as
• Tablets designed to dissolve quickly
study 23 in the report) because it upheld the eleven
(effervescent tablets) – limit dwell time in the
criteria required for study inclusion. The Macknin
et. al. study found zinc to have no effect on cold
• Limited controls for etiology (rhinovirus,
duration or severity. However, an independent per-
protocol analysis of this study showed that it was a
• The use of zinc sulfate, which is not used in
poorly controlled study. Roughly 74 percent of the
zinc lozenges and has not shown efficacy in
study participants could not be evaluated due to a
variety of issues, leaving only 64 subjects from the
original 248 participant pool. While this study met
Discussion
the inclusion criteria set by the report authors, its
There is significant evidence that zinc gluconate
results should not be used to evaluate the
glycine lozenges reduce the severity and duration of
effectiveness of zinc lozenges. (A per-protocol
analysis is available from The Quigley Corporation
A wide range of study on the subject has been
conducted, yielding inconsistent results. The primary
explanation for the inconsistencies between study
• Dr Robert Lambkin-Williams, Director and
results include differences in zinc preparations,
General Manager Retroscreen Virology Ltd,
including form (zinc gluconate versus zinc acetate),
University of London. Ph.D Avian Influenza,
dosage (elemental zinc per lozenge; range from 5 –
23 mg), and composition of lozenge (Hulisz 2004,
“The paper by Caruso et. al. reviewed a wide
range of zinc / rhinovirus clinical trials and
A recent report in Clinical Infectious Diseases
concluded, based on their criteria, that only a zinc
(Caruso 2007) reviewed 105 zinc studies. Of those,
gel applied directly to the nasal passage was
fourteen randomized controlled trials were selected
effective. They also suggest that migration of
to make a general conclusion that zinc gluconate
zinc ions from the oral cavity to the nasal sinuses
glycine lozenges are not effective against the
has been challenged. Unknown to the authors,
unpublished data from a controlled clinical trial
has shown that zinc ions can be detected after a
Finally, there was a recent report, that warned of
volunteer dissolves a lozenge in their mouth, thus
the use of the over the counter 'tussin' products
supporting a mode of action of zinc lozenges.
There is also published in-vitro data to support
inappropriate use has resulted in some serious
the mechanism of action of zinc ions against
consequences. This has not been my experience
The criteria that the authors used to review the
• Larry Stephens, B. S. Pharmacy, Licensed
papers were not unreasonable for a modern
Pharmacist, Community Hospital Practice,
clinical trial. The difficulty lies in reevaluating
clinical studies that were conducted many years
ago and to suitable standards at the time. In
“Virtually every researcher has their opinion on
addition, it would seem that only the papers were
what makes a valid design, and the eleven criteria
reviewed and it is possible that some of the
selected by the authors of the Echinacea paper,
criteria were included in the original design, but
subsequently used in the Zn paper, are yet
another example of this. I would like to hear from
those who designed the studies with less than, or
• Dr. Peter Lodewick, Endocrinologist, Clinician,
other than, the eleven criteria to see what valid
“I had a chance to review the article, Treatment
There are problems with at least one of the
of Naturally Acquired Common Colds with Zinc,
criteria determined to be valid in the Zn study by
by Caruso et. al., and I was quite surprised by
Caruso, et. al. Validated case definition is
their conclusions. As a clinician, both working as
dependant on the skill of the practitioner making
a diabetes specialist and an emergency physician
the diagnosis. Most practitioners will freely
over the years, my experience has been different.
admit that differential diagnosis between early
We know that most upper airway diseases of
flu, allergy and cold symptoms is very difficult.
acute onset are viral in origin. However, they can
If the initial determination is incorrect, and
provoke severe symptomatic illness, frequently
someone with an allergy is entered into a study
causing diabetes to go out of control, especially
using Zn to treat common cold symptoms, we
in patients with type I diabetes, maybe even the
serious diabetic ketoacidosis, if patients and their
family are not alerted as to preventive measures.
I have seen various forms of zinc gluconate used
It is imperative to be sure that the illness is not
recommended by their physician, and self-
bacterial in origin, so that an office visit to rule
medication in others. The opinions on results
out streptococal pharngitis or nonviral causes is
vary, but most patients report benefit, especially
definitely an important initial step. If it is viral in
for sore throat symptoms. Others say it lessens
origin, it has been my experience over the past 25
the time they are sick as compared to doing
years to use zinc gluconate lozenges (my
nothing and just ‘waiting it out’. Based on my
preferred brand, Cold-eeze). My patients have
experience and my opinion of relevant studies, I
done well using zinc lozenges, frequently
feel that zinc gluconate glycine (Cold-EEZE) has
reporting that they feel better, especially if they
value in the treatment of the common cold.”
use them within 24 hours of onset, more quickly.
It is also my opinion that the use of zinc lozenges
It may also be of interest to scientists and clinicians
may better in treating the common cold than to
that early research indicates that ionic zinc may have
use antibiotics, which may be called in over the
antiviral effects on other viruses such as herpes
phone, as the inappropriate use of antibiotics
simplex 1 and 2 viruses and infections in animals and
seems to be resulting in increasing resistance to
humans. More research is needed in these, and other
antibiotics, even streptococcus infections.
Conclusion Clinicians and patients must balance the benefits and risks of traditional over-the-counter cold remedies when
Nonpharmacological treatments and homeopathic options such as use of zinc gluconate glycine lozenges offer important alternatives. The use of zinc gluconate glycine lozenges has shown significant clinical benefit to patients in the reduction of the severity and duration of the common cold.
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