Dispel the Myths
ABOUT THE SAFETY OF
TO CIRCULATE, SCIENTIFIC
NOT ONLY THEIR SAFETY, BUT
THEIR EFFICACY AS WELL.
By Ann Eshenaur Spolarich, RDH, PhD, and JoAnn R. Gurenlian, RDH, PhD
Despite the large number of published papers
documenting the safety and efficacy of antimicrobial
mouthrinses, dental professionals
continue to struggle with product recommendations
because of concerns about toxicity and other adverse
events. Negative perceptions regarding mouthrinse safety
are often perpetuated by incorrect and misrepresented "factual"
information that has been republished for decades,
despite a lack of evidence to support these claims and the
presence of research that disputes these concerns. The
safety of alcohol-containing mouthrinses continues to
inspire debate for many clinicians who have become trapped
in this maze of misinformation.
WHY DOES ALCOHOL APPEAR IN
All mouthrinses that have received the American Dental Association
(ADA) Seal of Acceptance for safety and efficacy as antiplaque and
antigingivitis agents contain alcohol. Alcohol is added to
mouthrinse products to solubilize the active ingredients, making
them biologically active. Alcohol is also used to dissolve the flavoring
agents and as a preservative. Alcohol is not the biologically
active ingredient in any cosmetic or therapeutic
Essential oil mouthrinse contains 26.9%
alcohol in the traditional product and 21.6%
alcohol in the flavored products; 0.12%
chlorhexidine gluconate mouthrinses generally
contain 12.6% alcohol; and traditional
cetylpyridinium chloride products contain
alcohol levels ranging from 6% to 18%.
There are two alcohol-free products that
contain a higher concentration of cetylpyridinium
chloride (0.07%), neither of which
carries the ADA Seal.
IS ALL ALCOHOL THE SAME?
Commercial mouthrinse formulations contain
pharmaceutical alcohol, which is pure ethanol.
Alcoholic beverages contain ethyl alcohol,
which is produced through the fermentation
of vegetables, grains, or fruits, and is found in
products like beer and wine. Distilled beverages,
such as whiskey and vodka, are created
by collecting the dilute solutions of ethanol
that are produced through the fermentation
TOXIC EFFECTS OF ALCOHOL
The toxic effects of ethanol are associated
with its primary metabolite, acetaldehyde,
and secondary metabolite, acetic acid.
Acetaldehyde accumulation contributes to
the feeling of a "hangover" including nausea,
vomiting, dizziness, and headache.
Acute alcohol poisoning is associated with
alcohol overdose (toxicity), which can lead
to central nervous system depression. Signs
and symptoms of acute toxicity include loss
of consciousness, drop in blood pressure,
decreased body temperature, and respiratory
depression. Without intervention, acute alcohol
poisoning can be fatal.1
Chronic alcohol exposure is associated with
more than a dozen diseases, including numerous
cardiovascular disorders, neurological
impairments, liver disease, and gastrointestinal
complications.2 Fetal alcohol exposure is
associated with pregnancy and delivery
complications, birth defects, and intellectual
and developmental disabilities.3
There is no evidence that the chronic topical
use of alcohol-containing mouthrinses contributes
to toxic systemic effects because these
products are not swallowed or ingested in any
IS ALCOHOL CARCINOGENIC?
Alcoholic beverages contain numerous
additives and chemicals that are known to
cause cancer, one of which is urethane.4
These chemicals arise from the fermentation
and distillation processes in which
yeasts and plants convert pyruvate into
acetaldehyde, which is then converted to
ethanol, captured as the by-product in
Congeners are substances that are also produced
during fermentation, contributing to
the taste of both distilled and nondistilled alcoholic
beverages. However, congeners are considered
impurities that contribute to ethanol
toxicity and include fusel alcohols (highly
toxic), acetone, aldehydes (eg, propanol and
glycol), and acetaldehyde. Congeners are also
implicated in carcinogenesis.5
Long-term exposure to alcohol is associated
with cancer of the mouth, throat, esophagus,
liver, colon, and breast. Risk for developing
cancer increases with increased alcoholic beverage
ALCOHOL AND ORAL CANCER
Ethyl alcohol is metabolized to acetaldehyde,
which can be toxic to oral tissues, causing
DNA damage in the cells, leading to cell
mutation and carcinogenesis. This is why
chronic alcoholic beverage consumption is a
leading risk factor for oral and pharyngeal
Alcohol exposure also increases the permeability
of oral mucosal cell membranes,
allowing cellular DNA to become exposed
to toxins and other carcinogens.7,8 This
explains why many cases of oral cancer are
observed in chronic drinkers, chronic smokers,
or in people who drink socially and also
smoke.9 Laboratory data that demonstrate
increased cell permeability are based on
exposure of the cells to large amounts of
alcohol and exposures of 1 hour or longer,
which reflects what is observed during social
Oral bacteria have the ability to convert
alcohol to acetaldehyde, and the amount of
acetaldehyde produced is associated with
poor oral hygiene.9,10 About 15% of people
with oral cancer have no known risk factors,
thus, their cancer may be related to infections
associated with viruses (human papillomavirus),
fungi (Candida albicans), and
possibly by bacteria via acetaldehyde formation.
10 Certain species of oral bacteria may
locally produce enough acetaldehyde to
cause DNA damage, leading to cellular
mutation and hyperproliferation of the oral
epithelium.11,12 Yeasts have also been shown
to produce acetaldehyde from alcohol.13
Dental professionals must remember that
oral flora demonstrate multiple, pivotal roles
in oral cancer initiation by cellular mechanisms
other than acetaldehyde formation.
This must be kept in mind when considering
possible etiologic factors for cancer in their
Pure ethanol (pharmaceutical alcohol) has
never been found to cause cancer in any lab -
oratory (cellular, animal) or human model.5,9
Pure ethanol is not a carcinogen by itself nor
does it contain any added carcinogens.14 The
discussion about the role of alcohol-containing
mouthrinses and oral cancer has continued
for more than three decades. Early
studies examining the relationship between
alcohol-containing mouthrinses and oral
cancer yielded conflicting results.5,15–21 Critical
analysis shows numerous methodological
problems with these studies, including
failure to demonstrate a dose-response relationship
based on frequency and/or duration
of mouthwash use; failure to control for
alcohol ingestion and tobacco use; lack of a
biologic or scientific explanation for inconsistent
results; and inclusion of other cancers
of the head and neck, including pharyngeal
Recent investigations have shown that the
use of an alcohol-containing mouthrinse leads
to short-term formation of acetaldehyde that
is detectable in saliva for up to 10 minutes.
24–26 However, this increase is short-lived,
as salivary acetaldehyde levels drop to low
levels within 5 minutes, presumably due to
salivary ethanol metabolism.26 Salivary
acetaldehyde levels after rinsing with an
essential oil mouthrinse were significantly
lower than those seen after rinsing with an
equivalent ethanol control. This might be
explained by the effective antimicrobial activity
of essential oils by killing the bacteria
before they have the opportunity to metabolize
ethanol to acetaldehyde, or that other
ingredients in the mouthrinse stimulate salivary
flow, which dilutes its level.26 Ingestion
of alcoholic beverages also causes prolonged
salivary levels of acetaldehyde.27 Clinicians
should note that acetaldehyde is also found
naturally in the body, as well as in many fruits,
vegetables, and dairy and meat products.26 As
such, it is not practical to account for all
sources of exposure.
The topical exposure of oral mucosa to
alcohol from mouthrinses is not comparable
to consuming alcoholic beverages. Two
or even three topical exposures of a 25%
alcohol-containing mouthrinse, each lasting
30 seconds, seems unlikely to produce the
same effect as chronic, habitual alcohol
consumption. Assuming that the two- to
three-times-daily rinsing with alcohol-containing
mouthrinse is equivalent to consuming
one to two alcohol-containing
drinks per day, the current literature does
not document a higher risk for oropharyngeal
cancer with alcohol beverage consumption
at this level.23
Lachenmeier's group reports that "estimated
lifetime cancer risk for twice-daily
alcohol-containing mouthwash use (and
including additional acetaldehyde exposure
from other cosmetics) as being three to four
cases per 1,000,000."24,28 "The risk of alcohol-
containing mouthwash for public health
appears very low compared to other routes of
exposure to alcohol and acetaldehyde, so that
priority for risk management actions should
be placed rather on reducing alcohol consumption
Two investigations performed by the Food
and Drug Administration, in 1996 and 2003,
concluded that there was no relationship
between alcohol-containing mouthrinses and
oral cancer.4,14,29,30 The ADA also states that
there is no causal relation ship.30 Reviews of the
epidemiologic evidence have failed to link use
of alcohol- containing mouthrinses with oral
cancer.31–34 Few studies have described why
mouthrinse is being used, noting that it is
often used to mask drinking and smoking
behavior.34 Future studies need to control for
smoking and alcohol use, and document reasons
for, frequency and duration of use, and
particular type of mouthrinse used.34 Table 1
provides the findings of the most recent metaanalysis
of 18 epidemiologic studies of mouth -
rinse use and oral cancer.34
DOES ALCOHOL CAUSE ORAL
A common misconception is that the use of
an alcohol-containing mouthrinse would dry
(desiccate) the oral mucosa. However, two
published studies have shown that rinsing
with an essential oil mouthrinse produced
the exact opposite effect.
In a study of 19 women with Sjögren's
syndrome, salivary flow rates were measured
before and after rinsing with an
essential oil mouthrinse and a control
mouth rinse. Under exaggerated conditions
(three rinses per day instead of the recommended
two), post-rinsing salivary flow
rates were 28.2% higher in those rinsing
with an essential oil mouthrinse compared
to the control.35
A more recent investigation compared the
effect of exposure to an alcohol-containing
and a nonalcohol-containing mouthrinse on
salivary flow and perceptions of dry mouth.
Twenty healthy subjects were asked to rate
their level of perceived dryness before and
after rinsing. Then, subjects rinsed with either
an alcohol-containing mouthrinse or a
mouthrinse without alcohol. Salivary flow rates
increased post-rinse for both subject groups.
Subjects' perception of dryness was actually
lower before rinsing with both products.
There were no differences between rinsing
with the alcohol-containing mouthrinse and
alcohol-free mouthrinse in either objective
(flow rate) or subjective (perception) measures
Essential oil alcohol-containing mouth -
rinses are approved for use in children
older than 12. The efficacy and safety of
chlorhexidine in children under 18 have
not been established. Due to the potential
risk of alcohol ingestion, clinicians must
assess the child's ability to swish and
expectorate without swallowing prior to
Patients with a history of alcohol abuse
who are in recovery should be advised that
the use of an alcohol-containing mouthrinse
may induce relapse, and they should consult
with their abuse sponsor before using an
alcohol-containing mouthrinse. Manufacturers
generally state that these products are
contraindicated for use in patients either
with or recovering from alcoholism.23 Alcohol-
containing mouthrinses should also be
avoided when patients are using disulfiram
(Antabuse®), a drug used as a deterrent in
alcohol recovery programs, or metronidazole
(Flagyl®), an antibiotic. Concurrent use
can produce nausea, vomiting, dizziness,
Antimicrobial mouthrinses can reach difficult-
to-reach areas in the mouth, killing
bacteria that mechanical methods may
leave behind. By accessing all areas of the
mouth, antimicrobial mouthrinses reduce
salivary microflora and the overall microbial
load, thereby reducing bacteria that would
otherwise colonize to form oral biofilm.
Strong clinical evidence based on studies
of at least 6 months duration supports the
safety and efficacy of chlorhexidine and
essential oil alcohol-containing mouth -
rinses, with weaker evidence supporting
the use of cetylpyridinium chloride, to
reduce supragingival plaque and gingi -
vitis.38,39 Dental professionals should feel
confident that it is safe to recommend alcohol-
containing mouthrinses to designated
patients for daily home use for the prevention
and treatment of gingivitis. Claims of
oral cancer associations or increased dryness
PHOTOCREDIT : RUSSELL KIGHTLEY/SCIENCE PHOTO LIBRARY
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- Corrao G, Bagnardi V, Zambon A, La Vecchia C.
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- American Academy of Pediatrics, Committee
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- Ciancio SG. Alcohol in mouthrinse: lack of
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- Garro AJ, Liever CS. Alcohol and cancer. Annu
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- Baan R, Straif K, Grosse Y, et al. Carcinogenicity
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- Squier CA, Cox P, Hall BK. Enhanced
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- Howie NM, Trigkas TK, Cruchley AT, Wertz PW,
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- Iacopino AM. Surveillance spotlight: use of
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- Chocolatewala N, Chaturvedi P, Desale R. The
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- Pöschl G, Seitz HK. Alcohol and cancer.
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- Salaspuro MP. Acetaldehyde, microbes, and
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- Tillonen J, Homann N, Rautio M, Jousimies-
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- US Food and Drug Administration. Oral health
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- Blot WJ, McLaughlin JK, Winn DM, et al. Smoking
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- Weaver A, Fleming SM, Smith DB. Mouthwash
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- Kabat GC, Herbert JR, Wynder EL. Risk factors
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- Young TB, Ford CN, Brandenburg JH. An
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- Winn DM, Blot WJ, McLaughlin JK, et al.
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- Wynder EL, Kabat G, Rosenberg S, Levenstein
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- Silverman S, Wilder R. Antimicrobial
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- DePaola LG, Spolarich AE. Safety and efficacy
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- Lachenmeier DW, Gumbel-Mako S, Sohnius
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- Moazzez R, Thompson H, Palmer RM, Wilson
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From Dimensions of Dental Hygiene. April 2013; 11(4): 20–22, 24.