Alcohol is one of the most controversial and misunderstood ingredients used in cosmetic skincare formulation. It has a reputation for being drying and irritating and is thought to contribute to premature ageing, destroy skin cells and cause inflammation.
But is alcohol really the enemy it’s made out to be? We don’t think it is. In fact, we think it can be a good friend at times.
Here’s everything you need to know about alcohol in skincare so that you can decide for yourself…
What is alcohol?
Alcohol is a broad term for an entire family of chemicals. Alcohols are organic compounds characterised by one or more hydroxyl (-OH) group bound to a carbon atom.
There are 4 main types of alcohol used in cosmetic skincare formulation:
1. Ethanol
Also known as ethyl alcohol, drinking alcohol, or grain alcohol. It is generally listed as ‘alcohol’ on the ingredients (INCI) list.
Ethanol is manufactured through the fermentation of starch, sugar and other carbohydrates, mainly from fruit, vegetables and cereals.
Ethanol is used in cosmetic formulation for several reasons:
Preservative
Used as part of the preservation system of the product. Preservatives protect skincare products against contamination by microorganisms like harmful bacteria, yeast and mould.
Clean and disinfect the skin
Alcohol is sometimes used in products like toners, makeup removers and astringents to help remove oils, lipids and waxes from the surface of the skin and to disinfect the skin of bacteria.
Skin penetration enhancer
Ethanol can assist with enhancing absorption of certain active ingredients in a higher concentration to the deeper layers of the skin to increase their effectiveness.
Solvent
Ethanol serves to dissolve water-insoluble ingredients to create smooth cosmetic products that don’t separate.
Extraction
Ethanol can be used to extract active constituents from plants and herbs. It is a more effective solvent compared to water.
Improves product application
Ethanol’s viscosity - decreasing ability, meaning that it can decrease the thickness of liquid cosmetic products, combined with its ability to evaporate rapidly means that it can help improve product application. It helps cosmetic formulas spread and set swiftly and has a cooling effect.
The Science
Ethanol has earned a bad reputation for being drying, irritating, disrupting the skin’s barrier and for causing inflammation in the skin.
Michelle Wong, chemistry PhD, and content creator at Lab Muffin Beauty and Stephen Alain Ko, cosmetic chemist and skincare expert, of Kind of Stephen have made an informative video explaining that although there are a number of in vitro studies showing alarming effects of alcohol (skin cell death, inflammation, denaturing proteins and slowing enzyme activity) on isolated cells or isolated skin, they aren’t completely credible because applying alcohol on the skin is completely different from dispensing alcohol onto naked cells in a dish.
They highlight that the stratum corneum, the top layer of skin, is an excellent barrier that prevents substances from passing through to the living skin cells, and that with ethanol being extremely volatile and evaporating when applied to the skin, the conditions in the in vitro cell studies are not immediately pertinent to the use of alcohol in skincare. (1)
They also looked at clinical trials comparing the effects of soap and water versus alcohol hand rubs on skin irritation, dryness, inflammation, skin barrier disruption and dehydration. The findings from the trials were that even when a large amount of alcohol was applied to the skin, it didn’t have a big impact. (2)
Below is what the studies found pertaining to some of the key concerns about alcohol in skincare:
- Inflammation
Inflammation is a sign of an immune response in the skin during which it repairs damaged tissue whilst simultaneously defending itself against harmful internal and external factors. A growing amount of evidence suggests that skin inflammation is linked to premature ageing and chronic autoimmune skin conditions like dermatitis and rosacea. Skin inflammation usually presents as redness, itching and swelling.
Although ethanol seemed to be able to initiate the release of inflammatory markers in some in vitro studies, scientists found that ethanol didn’t appear to be connected to a change in redness, compared to no ethanol. (3)
- Skin Barrier Disruption
There are in vitro studies that indicate that ethanol can extract measurable amounts of lipids from the skin and cause transient disorder to the intercellular lipids of the skin. It’s thought that this is how ethanol helps ingredients penetrate into the skin more effectively.
But Michelle and Stephen point out that the findings are inconsistent and that in many of the studies there weren’t significant negative effects on the skin samples, even when exposed to ethanol for long periods of time. Additionally, several of the studies indicated that the conditions don’t truly reflect how alcohol is used in skincare. (4)
- Skin Dehydration
According to Michelle and Stephen, the results from clinical trials as to whether alcohol decreases skin hydration are mixed. Some found that alcohol decreases skin hydration while others found that it does not. (5)
They also note that an alternative study found that the addition of moisturising ingredients, like fatty alcohols and glycerine, to a propanol-based hand rub can decrease skin irritation and dryness. (6)
2. Denatured Alcohol
Denatured alcohol (INCI Alcohol Denat or SD Alcohol) is ethanol with added denaturants, like methanol, to make it unsuitable for consumption. It is used as a cheaper alternative to ethanol in mainstream cosmetic formulation.
3. Fatty Alcohols
Fatty alcohols are solid, wax-like components of natural fats and oils. They are typically long-chain molecules. They have several functions in cosmetics and a different effect on the skin compared to ethanol.
Thickening Agents
They are used as natural thickening agents.
Emollients
Their good emollient properties help restore surface lipids, soften and smooth the skin without leaving it feeling greasy.
Co-emulsifier and Stabiliser
Fatty alcohols help bind the oil and water components of emulsions and stabilise them to keep them from separating.
Commonly used fatty alcohols:
Behenyl alcohol is derived from vegetable sources such as corn. It is used as an emollient, thickener, stabiliser and co-emulsifier.
Cetearyl alcohol is a blend of fatty alcohols, primarily cetyl and stearyl alcohols. Cetyl alcohol is obtained from vegetable oils such as palm or coconut oil and stearyl alcohol is derived from stearic acid, a saturated fatty acid. It is used as a surfactant, co-emulsifier, thickening agent, emollient and emulsion stabiliser.
Cetyl alcohol is an effective emollient extracted from vegetable oils such as coconut or palm oil. It also offers emulsifying, stabilising, foam boosting and viscosity controlling properties.
Stearyl alcohol is derived from stearic acid, a naturally occurring saturated fatty acid found in coconut oil. It is used as an emollient, emulsifier and thickener.
4. Aromatic Alcohols
Aromatic alcohols are predominantly used for fragrance and as a preservative.
Commonly used aromatic alcohols:
Benzyl alcohol is an alcohol that naturally occurs in certain fruits, like apricots, and a variety of essential oils, like ylang-ylang and jasmine. Benzyl alcohol functions by killing or preventing the growth of a broad spectrum of bacteria, yeasts and moulds and imparts a floral-like scent to cosmetic products. Although irritating in high amounts, it is considered safe at the small concentrations in which it is used in cosmetics. While naturally occurring, it can be synthetically produced in the laboratory by mixing benzyl chloride with sodium hydroxide.
Phenethyl Alcohol is produced by microorganisms, plants and animals and is naturally found in some essential oils like rose, neroli or geranium, certain foods, spices, tobacco and in undistilled alcoholic beverages. It imparts a rose-like fragrance to skincare products and protects them from spoilage by preventing bacterial growth.
Aromatic alcohols are considered safe in small concentrations and the potential for allergenicity is low, but they can be an irritant and cause itching for some people.
In conclusion, scientific findings show that fatty alcohols are beneficial in skincare and that a small amount of ethanol is quite harmless, especially when combined with skin nurturing ingredients.
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References
(1) https://bit.ly/3go3OZ2 https://bit.ly/3g3GqRz
(2) https://bit.ly/3gn60jp
(3) https://bit.ly/3gn60jp https://bit.ly/3gnW35g https://bit.ly/2TTWvAU https://bit.ly/3w6x9hb https://bit.ly/2RCNfAr
(4) https://bit.ly/3v0A3mB https://bit.ly/3pBzG0o https://bit.ly/3v0epyI https://bit.ly/3gi77Bb https://bit.ly/2RFnpf8 https://bit.ly/2SoomIV https://bit.ly/3v6TNEQ
(5) https://bit.ly/3wai3aw https://bit.ly/352r8GM https://bit.ly/2SdDFo0 https://bit.ly/3pAXr8Z
(6) https://bit.ly/3wai3aw https://bit.ly/2Teg9Y4