Ethanol is found in various products that are used topically on the skin. This includes pharmaceutical preparations, cosmetics, hairsprays, mouthwashes, and household products. The FDA has classified ethanol as a generally recognized as safe substance (GRAS). One ingredient associated with an increased risk of oral cancer is acetaldehyde.
Ethanol eliminates microorganisms such as bacteria, fungi and viruses which explains its use in many hand sanitizer products. Ethanol along with ether, chloroform and chlorine-containing disinfectants will deactivate the SARS-CoV2 virus. During the COVID-19 pandemic outbreak, hand sanitizers were essential for proper hand sanitization. Many formulations were available, including antimicrobial soaps, water-based and alcohol-based sanitizer. Topical ethanol will penetrate the skin and lead to transepidermal absorption of xenobiotics. Side effects associated with alcohol based hand sanitizers (ABHS) include skin irritation, allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). ICD symptoms will present as erythema, dryness, pruritus and bleeding. Those with an aldehyde dehydrogenase (ALDH) deficiency are especially at risk for adverse effects associated with topical ethanol use.
Ethanol is a solvent due to its ability to mix easily with water and other organic compounds. Many mouthwashes contain percentages of ethanol that are over 20%. Ethanol is commonly found in all these products, and there are concerns regarding ethanol’s carcinogenicity. There are some epidemiological studies available on the link of ethanol use in the oral cavity through mouthwashes and oral cancer, due to ethanol’s cytotoxicity. Ethanol will affect the cells lining the oral mucosa which promotes cell division of stem cells to regenerate epithelium.
The International Agency for Research on Cancer (IARC) concluded that alcohol consumption will lead to tumor formation in the oral cavity, larynx, pharynx, esophagus and female breast. However, there is lack of evidence that proves topical ethanol use will increase risk of skin cancer. Chronic alcohol usage will lead to certain skin issues including delayed wound healing, cellulitis and necrotizing wound infections. In transdermal patches, ethanol proved to be one of the causes for allergic contact dermatitis and cutaneous intolerance. Animals studies have shown that both acute and chronic consumption of ethanol will increase transdermal absorption through increased transepidermal water loss, which predisposes the skin to xenobiotics such as herbicides.
Lachenmeier DW. Safety evaluation of topical applications of ethanol on the skin and inside the oral cavity. J Occup Med Toxicol. 2008;3:26. Published 2008 Nov 13. doi:10.1186/1745-6673-3-26
Jing JLJ, Pei Yi T, Bose RJC, McCarthy JR, Tharmalingam N, Madheswaran T. Hand Sanitizers: A Review on Formulation Aspects, Adverse Effects, and Regulations. International Journal of Environmental Research and Public Health. 2020; 17(9):3326. https://doi.org/10.3390/ijerph17093326
Ethanol (Ethyl Alcohol). ChemicalSafetyFacts.org. Published 2021. Accessed 2021 June 4. https://www.chemicalsafetyfacts.org/ethanol/
Calderón-Montaño, J.M., Jiménez-Alonso, J.J., Guillén-Mancina, E. et al. A 30-s exposure to ethanol 20% is cytotoxic to human keratinocytes: possible mechanistic link between alcohol-containing mouthwashes and oral cancer. Clin Oral Invest 22, 2943–2946 (2018). https://doi.org/10.1007/s00784-018-2602-z
Ethanol is used in countless products with the intention of direct application to the skin. Examples include hand sanitizers as well as hairspray or mouthwash.
See source 1: The first and foremost concerns of topical ethanol applications for public health are its carcinogenic effects, as there is unambiguous evidence for the carcinogenicity of ethanol orally consumed in the form of alcoholic beverages. So far there is a lack of evidence to associate topical ethanol use with an increased risk of skin cancer. Limited and conflicting epidemiological evidence is available on the link between the use of ethanol in the oral cavity in the form of mouthwashes or mouthrinses and oral cancer. Some studies pointed to an increased risk of oral cancer due to locally produced acetaldehyde, operating via a similar mechanism to that found after alcoholic beverage ingestion.
Listerine is a well-known brand of mouthwash which was originally formulated using ethanol. Its purpose was to allow essential oils mix with the water base as well as act as a preservative. Research is undergoing as to validate suggestions that ethanol exacerbates xerostomia and increased risk for oral cancer.
In comparison to antibiotics, ethanol-containing mouthwash can kill almost all bacteria in your mouth – both good and bad. This is the same effect of antibiotics in gut microbiome health.
Many healthcare professionals have experienced dry skin especially with frequent use of hand sanitizers or direct alcohol sprays onto the hands during the COVID-19 pandemic. The American Academy of Dermatology Association recommends applying hand cream or ointment to your skin while your hands are slightly damp. Fragrant-free and dye-free products that are mineral oil or petrolatum based tend to feel less irritating to chapped skin.
Ethanol is a primary alcohol that is commonly used as a disinfectant, antiseptic, polar solvent, or CNS depressant among many other applications. Its disinfectant and antiseptic properties are due to the dehydration and precipitation of cell cytoplasms or protoplasms. It can also denature proteins, contributing to cell death. In alcoholic beverages, ethanol can cause CNS depression, leading to effects like sedation, loss of coordination, dizziness, blurred vision, and more. Excessive, long-term consumption of alcoholic beverages and use of mouthwash products containing ethanol have been linked to cancers of the mouth and throat, and topical ethanol use may be associated with skin cancers. However, the evidence pointing to ethanol as a carcinogen is not yet conclusive. Topical ethanol use may cause skin cancer due to its role as a skin penetration enhancer, allowing for carcinogenic compounds and UV rays to penetrate the skin more easily. More commonly, topical ethanol application can cause contact dermatitis which is usually mild. Another concern with topical ethanol use is that it can get absorbed by the skin to enter the bloodstream and negatively affect other susceptible organs. The proposed mechanism of oral cancer carcinogenesis is the production of acetaldehyde in the oral cavity. The risk of esophageal cancer after chronic alcohol consumption is even greater in people with deficient aldehyde dehydrogenase, the enzyme responsible for the catabolism of ethanol. Metabolism of ethanol also produces reactive oxygen species that bind to DNA in cells. Alcohol abuse has been identified as a possible risk factor for skin conditions like psoriasis, discoid eczema, and delayed wound healing. The mechanisms for ethanol-related skin conditions are not fully understood and theories are considering suppression of the immune system or altered lipid metabolism. In mouthwashes containing ethanol, the oral mucosa may be damaged by the ethanol, causing cell regeneration, which may get intercepted by genetic changes or carcinogenic substances that lead to cancers. Most of the data observed comes from animal studies, so there is not enough evidence yet to ban the use of ethanol on the skin and oral cavities.
National Center for Biotechnology Information. PubChem Compound Summary for CID 702, Ethanol. https://pubchem.ncbi.nlm.nih.gov/compound/Ethanol. Accessed Mar. 11, 2021.
Ethanol is a colorless liquid that is often used as a solvent or preservative in many products. Ethanol can be found in mouthwashes, fabric softeners, hand sanitizers and more. Ethanol can come in contact with the skin and oral cavities on a daily basis with chronic uses leading to damaging effects: poor wound healing, skin infections, cancer development, and liver disease. The safety and efficacy of local application of ethanol on the skin or oral cavities is still the topic of concern. Leading to experts saying that ethanol can cause serious damages to the skin, while saying that those damages are not as significant as the effects on the liver and nervous system. Some researchers are even stating that ethanol is relatively safe when used topically with little data to back up these claims if ethanol was used chronically.
The COVID-19 pandemic has prompted the widespread use of ethanol-based hand sanitizers. Chronic use of these ethanol hand sanitizers can be damaging to the skin as well. It can cause manipulation of the intercellular lipids and destruction of skin proteins. The manipulation of lipids on the skin can allow the ethanol to seep into the pores and change skin flora. This could lead to more frequent infection of foreign bacteria because of the irritating and drying effect that ethanol also has on the skin; leading to cracks that can form and further permeate through the cutaneous layer. To combat this, patients are recommended to avoid irritating ethanol-based substances and moisturize their skin using humectants or emollients.
The FDA puts restrictions on the amount of ethanol that can be used in products. For example, the FDA only allows up to 5% of ethanol in medical products for children. Other products such as mouthwashes usually contain 7-25% of ethanol. Research shows that ethanol greater than 5% can inhibit fibroblast proliferation and negatively morphs the cells at both low and high concentrations. However, the cells that line the oral cavity are more likely to recover with mouthwashes that contain a lower percentage of ethanol compared higher concentrations. Animal studies have also shown that ethanol can increase the reactive oxygen species in oral fibroblasts. Thus, leading to TNF-a production in periodontal fibroblasts. Ethanol can also affect cytokine production as well as T-cell function. Alternatively, many mouthwashes contain chlorhexidine which does not have the damaging effects in the oral cavity and is the real driving force to stimulate wound healing.
Jing, J., Pei Yi, T., Bose, R., McCarthy, J. R., Tharmalingam, N., & Madheswaran, T. (2020). Hand Sanitizers: A Review on Formulation Aspects, Adverse Effects, and Regulations. International journal of environmental research and public health, 17(9), 3326. https://doi.org/10.3390/ijerph17093326
Lachenmeier, D.W. (2008). Safety evaluation of topical applications of ethanol on the skin and inside the oral cavity. J Occup Med Toxicol 3, 26. https://doi.org/10.1186/1745-6673-3-26
Wyganowska-Świątkowska M, Nowak A, Paszyńska E, Grzech-Lesniak K. (2018). Ethanol influence on gingival fibroblasts - a real-time in vitro study. Ann Agric Environ Med. 25(4):647-650. doi: 10.26444/aaem/78696. Epub 2017 Nov 15. PMID: 30586975
Ethanol is a clear, colorless liquid that is known for its CNS depressant psychoactive effects. What the majority of the public doesn’t know, is that ethanol holds bactericidal activity and can be used as a disinfectant. This includes hand disinfectants including hand sanitizers (which are being used quite often by the general public nowadays). It is also used in mouthwashes, aerosol paints, hair coloring, and nail polish and polish removers. Ethanol acts on the GABA receptor as an agonist. It is converted from ethanol to acetaldehyde in the body which is more toxic than ethanol itself.
Ethanol used on the skin can cause a wide variety of skin conditions. This includes psoriasis, eczema, superficial infections, and delayed wound healing due to ethanol’s drying effect. Ethanol causes these conditions because it suppresses the immune system, causes liver disease, influences lipid metabolism, and also can affect keratinocytes.
The World Health Organization has been doing research on ethanol as a carcinogenic agent. It has been learned that ethanol of alcoholic beverages has been associated with tumors of the oral cavity, pharynx, larynx, esophagus, liver, colorectum, and female breasts. These tumors are a result of the pituitary- mediated mechanism which decreases carotenoid antioxidants in the skin which can cause erythema to occur faster. Ethannol also has an interaction with aloe barbadensis which is found in skincare products. Also, barbadensis transforms ethanol into acetaldehyde, which as noted before, is more toxic than ethanol itself.
In a meta-analysis done with 229 studies, it was concluded that greater alcohol consumption was associated with a greater risk in several different types of cancer but mostly cancers of the oral cavity, pharynx, esophagus, and larynx. Esophageal and liver cancers were also more apparent in the male populations of these studies. It was concluded that alcohol consumption of at least 50 grams per day significantly increased the risk of developing any type of alcohol-related cancer.
Ethanol, when applied to the skin, removed the lipid layer from the stratum corneum. This lowers the skin barrier function and makes the membrane more permeable. This is great when it increases the skin’s permeability for medications. But the permeability is also increases ones exposure to xenobiotics and other carcinogens found in the air and topical cosmetics. This can also increase a patient’s risk of reactions that result in a rash or contact dermatitis.
Ethanol can also be used in mouthwashes and oral rinses because of its bactericidal effects. While it kills bacteria, it can also damage the mucosa and lead to stimulation of cell regeneration that can develop into dysplasia, leukoplakia, and other forms of cancer. The damage to the mucus membrane can also increase the absorption of carcinogenic substances. The conversation of ethanol to toxic acetaldehyde is also done in the oral activity which can be the cause of some of the toxic effects. A double-blinded study was done in San Jose, Costa Rica that showed using an alcohol-free mouthwash containing 0.075% cetylpyridinium chloride (CPC) and 0.05% sodium fluoride (NaF), significantly reduced dental plaque and gingivitis. This study shows that a mouthwash does not need alcohol to effectively reduces dental plaque and gingivitis. This is why there is an increase of mouthwashes on the market without any alcohol content.
Alcohol Consumption and the Risk of Cancer. National Institute on Alcohol Abuse and Alcoholism. https://pubs.niaaa.nih.gov/publications/arh25-4/263-270.htm. Accessed January 29, 2021.
Ayad F, Prado R, Mateo LR, et al. A comparative investigation to evaluate the clinical efficacy of an alcohol-free CPC-containing mouthwash as compared to a control mouthwash in controlling dental plaque and gingivitis: a six-month clinical study on adults in San Jose, Costa Rica. J Clin Dent. 2011;22(6):204-212.
Ethanol has quickly become a chemical heavily involved with numerous topical products; most popularly utilized as an antiseptic agent in topical agents such as hand sanitizer, ethanol is regarded as a chemical staple. Outside of the realm of cleaning products, ethanol is also present in numerous skincare applications--and though its presence can be considered ubiquitous, the safety of ethanol on the skin should be assessed thoroughly. While up to date literature on the effect of ethanol upon the skin and oral cavities is lacking, previous data & research shows conflicting evidence behind the consequences of ethanol use as a topical preparation and on the oral cavities.
One of the most important facts to consider is the supposed connection between ethanol use and potential for skin cancer formation. While the connection between the two has yet to have been properly clarified, many argue that the formation of acetaldehyde from ethanol may be something that contributes to the eventual formation of malignancies. The mechanism behind the formation of acetaldehyde is thought to be akin to its formation upon ingestion of alcohol. In addition, another mechanism by which ethanol may induce carcinogenic activity is by the fact that ethanol, by nature, may be responsible for enhancing skin penetration. This enhancement may, in turn, ultimately allow for xenobiotics to sink into the skin. Xenobiotics may include carcinogenic or mutagenic products, therefore increasing the likelihood of the formation of an ultimate malignancy.
In addition to the potential for a malignancy forming after continued topical ethanol use, it has also been associated with causing skin dermatitis and irritation. Ethanol as a skin irritant is more often found in patients who possess a deficiency of Aldehyde Dehydrogenase, an enzyme that helps facilitate the breakdown of alcohols into ketones and aldehydes. In addition, continued ethanol use can lead to excess skin dryness, leading to a cycle of flaking that will require further exfoliation. In addition to topical ethanol use and its consequences, excessive ethanol consumption can lead to the exacerbation and worsening of certain skin conditions, such as psoriasis, eczema, and rosacea. Many believe that the mechanism behind this includes the suppression of the immune system. In spite of the supposed risks that ethanol use entails when applied topically or in the oral cavities, studies have shown that transdermal absorbent of alcohol through application on the skin (namely, through hand sanitizers during the COVID-19 pandemic) has been shown to be below the level determined to be the threshold of toxic ethanol absorption.
In conclusion, ethanol is considered a multipurpose chemical with numerous beneficial effects. Used most often as a sanitizing agent due to its disinfectant properties, ethanol can also be utilized as an excipient to enhance skin penetration of other xenobiotics; while this property is an asset when administering medication transdermally, such a feature of ethanol can inadvertently encourage the absorption of compounds that are considered mutagenic or carcinogenic. In addition, patients who have an ALDH deficiency may also experience a build up of aldehydes, further enhancing the formation of carcinogenic chemicals. Overall, ethanol shows numerous benefits but the consequences of the chemical must also be considered carefully.
Ethanol is a multi-use product that is included in products that have direct exposure on the human skin such as cosmetics , mouthwash, and pharmaceutical preparations. The major concern researchers have with topical ethanol applications in the consumer setting is that there could be carcinogenic effects that could be developed from long term use. This comes from the evidence that ethanol can have carcinogenic properties when consumed in the form of alcoholic beverages. Recent studies have found a lack of evidence to associate topical use with an increased risk of skin cancer. Likewise, there is limited and conflicting evidence available on the link between the use of ethanol in the oral cavity found in some mouthwashes or mouth rinses and oral cancer. Ethanol is included in a lot of products that are used by the population on a daily basis, so it is concerning to know that there could be a risk in cancer with these products.
You can find alcohol in a variety of skin care products including makeup, lotions, and fragrances. The FDA defines alcohol as a large and diverse family of chemicals with different names in a variety of excellent skin. A few reasons as to why alcohol would be added in cosmetic products is because it will make the product feel more elegant, lighter, and can also improve the overall feeling of the product by making it absorb faster into the skin. In addition, alcohol is also a preservative that can be used in products to keep them available long-term use. Alcohol such as ethanol, isopropyl alcohol, and methanol can cause dryness, irritation, and breakouts when added to skin care. When used in high concentrations, they can deteriorate your skin’s protective barrier which means your skin will no longer be effective at keeping moisture in. Other alcohols like the fatty alcohols that are derived from vegetables can help emulsify cosmetics, so the oil and water in them doesn’t separate. These alcohols are not drying or irritating to the skin at all. In fact , they have the opposite effect. Fatty alcohols can act as an emollients which protect your skin and help keep it moisturized. Overall, topically applied ethanol products can act as a skin penetration enhancer and may facilitate the absorption of xenobiotics or carcinogenic contaminants. In people with an aldehyde dehydrogenase deficiency , ethanol use can be associated with skin irritation or contact dermatitis. After regular application of ethanol on the skin, measurable blood concentrations of ethanol and its metabolite acetaldehyde can form. This becomes a concern especially in children, who have lacerated skin and are at risk to a percutaneous toxicity.
Increasing evidence suggests that acetaldehyde which is a metabolite of ethanol carries carcinogenic properties that that can be found in alcoholic beverages. Most ready to use mouthwashes typically have between 5 to 27% of ethanol in them, and an increased risk of oral cancer has been discussed from users of such mouthwashes. However, there is little evidence that links these two things together and the results remain inconclusive. In studies done, the local acetaldehyde contents in the saliva are reaching concentrations associated with DNA mutation and sister chromatid exchange, in vitro. These risk factors can be associated with some concern for local carcinogenic effects in the oral cavity.
Lachenmeier DW. Safety evaluation of topical applications of ethanol on the skin and inside the oral cavity. J Occup Med Toxicol. 2008 Nov 13;3:26. doi: 10.1186/1745-6673-3-26. PMID: 19014531; PMCID: PMC2596158.
Lachenmeier, D.W., Gumbel‐Mako, S., Sohnius, E.‐M., Keck‐Wilhelm, A., Kratz, E. and Mildau, G. (2009), Salivary acetaldehyde increase due to alcohol‐containing mouthwash use: A risk factor for oral cancer. Int. J. Cancer, 125: 730-735. https://doi.org/10.1002/ijc.24381
Written by: Denise Cotter and Niyati Doshi
Ethanol is a clear, colorless liquid that is used for its bactericidal activity for disinfection. This is also a widely used product in pharmaceutical preparations, alcoholic beverages, hand disinfectants, hairsprays, mouthwashes, fabric softeners, aerosol paint concentrates, hair coloring, laundry detergents, nail polish, and polish removers. Ethanol might be useful as a disinfectant, especially now to disinfect many surfaces across the country due to COVID-19, there are concerns that topical use of ethanol can have carcinogenic effects. Ethanol can affect the skin by leading to psoriasis, discoid eczema, and superficial infections. These can develop due to alcohol abuse. Chronic alcohol abuse can also lead to necrotizing wound infections, delayed wound healing, and cellulitis. There are also theories that include alcohol consumption causing the previously mentioned diseases, immune suppression, malnutrition, and liver disease. Cirrhosis is known to be caused by alcohol abuse, but the metabolism of alcohol can also potentially explain the dermatologic diseases that can be triggered. There are not many studies on this topic, but there was interest shown that the stimulatory effect of ethanol on human keratinocytes can lead to psoriasis with the misuse of alcohol.
Currently in the height of COVID-19, many are using hand disinfectants which contain ethanol. This is for the purpose of making sure they are sanitizing their hands but also making sure they are trying to keep safe from the virus. These products were more widely used in hospitals and healthcare settings, but now they are being used on a daily basis by everyone. Although, this is not for consumption, it should still be taken as a precaution because there is no determined study on whether or not ethanol-based hand disinfectants are safe or not. No significant changes were seen when constantly rubbing the sanitizer or disinfectant into the skin but a decrease in skin hydration was noticed, there was no harm seen, but this can cause irritation to those who already have dry skin and have rougher patches of skin. For the most part, alcohol based sanitizers being used on the skin do disinfect and do not really show that it causes much harm or absorption, but it should be still used with precaution, as more studies and evaluations should be done to make a more definitive statement on the safety in topical use of ethanol as a disinfectant.
In 2007, WHO’s International Agency for Research on Cancer (IARC) reported that ethanol in alcoholic beverages is classified as carcinogenic to humans. Malignant tumors were seen in the oral cavity, pharynx, larynx, esophagus, liver, colorectum, and female breasts. This study was observed with different types of alcoholic beverages and in correlation to carcinogenicity of ethanol in animals, due to this the IARC considers ethanol itself without any other additive product to be the causative agent of carcinogenicity in alcoholic beverages. Consuming about 50 grams of alcohol (ethanol) on a daily basis increases the risk of the previously mentioned cancers about two to three times more compared to a non-drinker. A higher risk of oesophageal cancer is seen in those who consume alcohol and lack the enzyme aldehyde dehydrogenase, which catabolizes ethanol. This leads to confirmation that acetaldehyde from ethanol is carcinogenic. In regards to this, it should also be precautioned to the population to limit their consumption of alcohol, as it might cause carcinogenic effects.
G. Kampf, A. Kramer, et al. “Quantity of Ethanol Absorption after Excessive Hand Disinfection Using Three Commercially Available Hand Rubs Is Minimal and below Toxic Levels for Humans.” BMC Infectious Diseases, BioMed Central, 1 Jan. 1970, bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-7-117.
Lachenmeier, Dirk W. “Safety Evaluation of Topical Applications of Ethanol on the Skin and inside the Oral Cavity.” Journal of Occupational Medicine and Toxicology (London, England), BioMed Central, 13 Nov. 2008, www.ncbi.nlm.nih.gov/pmc/articles/PMC2596158/.
Use of Ethanol on the Skin and Oral Cavities - Dr. Michelle Lam
Power Point & Script
A disinfectant, preservative, and solvent, ethanol is a clear, colorless liquid chemical that has been very popular recently. Since the pandemic of COVID-19, the use of disinfectants have skyrocketed as a mean to halt the spread of the virus. Ethanol, however, can be found in more products than just disinfectants: it can also be found in hairsprays, mouthwashes, fabric softeners, hair coloring, laundry detergents, as well as nail polish and polish removers. And although a very effective disinfectant, ethanol can have various effects on the skin. It can cause psoriasis, eczema, superficial infections, cellulitis, and can also delay wound healing. This is largely because ethanol enters the skin and removes lipid barrier from stratum corneum; which extracts lipids and proteins from the mucosa and causes cutaneous reactions or allergic contact dermatitis. This also lowers skin barrier function making the membrane more susceptible to higher exposure of xenobiotics, tobacco carcinogens, or nitrosamines found in cosmetics. The other factors that come into play are patient specific features like immune suppression, malnutrition, and liver disease. The effect of ethanol in mouthwashes on oral cavities is somewhat similar. Mucosa damaged by ethanol can lead to stimulation of cell regeneration and the subsequent development of dysplasia, leukoplakia and cancer. Damage to the mucous membranes can also increase absorption of carcinogenic substances. Furthermore, ethanol can be oxidized into toxic acetaldehyde in the oral cavity or when ingested. WHO’s International Agency for Research on cancer considers ethanol as causative of carcinogenicity of alcoholic beverages. Studies show that 50g of ethanol daily increases risk of cancer by 2 - 3 times. For this reason, as pharmacists, it’s wise to advise our patients to always limit the use of ethanol containing products, especially for those with a history of allergic reactions.
National Center for Biotechnology Information. PubChem Database. Ethanol, CID=702, https://pubchem.ncbi.nlm.nih.gov/compound/ethanol#section=Top (accessed on June 10, 2020)
Ethanol is a chemical compound and simple alcohol with bactericidal activity that is often used as a disinfectant. It is present in many products that may have direct contact with the skin: hand disinfectants, cosmetics like hairsprays and mouthwashes, pharmaceutical preparations, laundry detergents, and many household cleaning products. In the pharmaceutical industry, it is used a solvent or preservative.
There have been some concerns about the safety of ethanol on the skin and in oral cavities. While evidence is limited, some studies point to a possible link between use of ethanol in oral rinses and increased risk for oral cancer. A possible mechanism may involve the conversion of ethanol to acetaldehyde in the body, which is more toxic than ethanol itself. While current evidence is contradictory, people may substitute with alcohol-free mouthwashes, which have been shown to be just as effective as alcohol-containing ones.
Ethanol can also act as a skin penetration enhancer when applied topically. It can enter the skin and extract lipids and proteins from the stratum corneum. This compromises the skin’s barrier function, increasing membrane permeability and facilitating absorption of xenobiotics or carcinogenic contaminants found in cosmetic products. In addition, ethanol can cause skin irritation or contact dermatitis. People with an aldehyde dehydrogenase (ALDH) deficiency are at increased risk for irritation due to decreased ethanol metabolism. Topically applied ethanol on un-lacerated skin is not known to cause acute or systemic toxic effects. The exception is children, who are at higher risk for ethanol toxicity through skin absorption, especially through lacerated skin.
In conclusion, further research is needed on the safety of topical ethanol application to better understand the possible long-term risk associated with it. In the meantime, the necessity of ethanol in topical products should be carefully evaluated.
Lachenmeier DW. Safety evaluation of topical applications of ethanol on the skin and inside the oral cavity. J Occup Med Toxicol. 2008;3:26.