Alcohols and Your Skin: The Good, The Bad, and the Ugly
For label-conscious consumers, spotting ‘alcohol’ in a skincare product is a red flag. But before you yank it out of your shopping cart, here are a few things you should know about alcohols – some may surprise you!
Alcohols Span A Wide Range
To start with, ‘alcohol’ is a generic term. To a chemist, an alcohol is basically any compound which includes carbon atoms (an organic compound) and an oxygen atom bonded to a hydrogen atom (called a hydroxyl group). There are thousands of those! They include alcohol in drinks, in gasoline, in hand sanitizers, but also substances derived from plant oils which feel and behave nothing like the disinfecting alcohol you might keep in your cabinet.
Differences stem primarily from the number of carbon atoms in alcohol molecules. Roughly stated, the hydroxyl group is attracted to water while carbon atoms are not. When bound to a short, “low-weight” carbon chain, the water-loving hydroxyl group makes alcohol an effective solvent. Heavier alcohols – with long carbon chains – are instead binding agents, emollients and thickeners.
The Light Weights
Ethanol and Isopropyl Alcohol
It turns out that the alcohol behind the bar is also used in skincare. Ethanol, the alcohol obtained from the fermentation of fruit or grain sugars, is essentially the same as Ethyl alcohol and Alcohol Denat which appear on cosmetics and skincare labels.
🚗 Drinking alcohol – and ethyl alcohol in skincare – are fundamentally the same as ethanol biofuel, fermented from corn or sugarcane! Ford’s Model T ran on a mix of gasoline and ethanol. Fast forward: in 2005, Congress set requirements for the use of renewable fuels, including ethanol – most gas now sold in the US is about 10% fuel ethanol.
⚗ Under the Prohibition, industrial ethanol could only be sold if additives made it poisonous to drink. To this day, “denaturing” alcohol ensures that consumer products cannot be turned into drinkable alcohol.
Rubbing alcohol? It too is found in skincare, as isopropyl alcohol or isopropanol.
Skincare products use ethanol, isopropyl alcohol and other low-molecular-weight alcohols for three basic reasons, each with a downside for skin health.
👉First and foremost, these alcohols help dissolve other ingredients in water-based solutions and they evaporate quickly. The result is a product which feels light and dries quickly. But as they evaporate, they often will also remove water from your skin!
👉Next, they enhance the absorption of active ingredients. Skin is 60-70% water and small alcohol molecules can penetrate skin cells by binding to their water, paving the way for beneficial compounds. (This is also largely how the alcohol you drink moves into your blood.) But any present irritants and allergens can be absorbed just as easily.
👉Third, simple alcohols are also quite good at dissolving sebum oil. Hence their use in cleansers targeted at oily skin. But alcohol-based cleansers tend to go overboard, stripping skin of its protective lipids. There are also concerns that alcohol might directly damage skin cell membranes.
Aromatic alcohols are another group of low-weight alcohols, used to stabilize scents in addition to their role as preservatives. Prime among them is benzyl alcohol. Aromatic alcohols – and the fragrances where they are found – are widely recognized as potential allergens.
Should you avoid all light-weight alcohols?
According to the American Academy of Dermatology, if you know your skin to be sensitive or if you have a skin condition like rosacea and eczema, you indeed probably should, especially in leave-on products. Otherwise, you might be ok when these alcohols are at the very bottom of the ingredient list.
But there are better alternatives in most cases. You will not find ethanol, isopropyl alcohol, benzyl alcohol, and their relatives on Bytewrthy.
Be aware that for the FDA, “alcohol-free” labelling narrowly means ethanol-free.
The Heavy Weights – Fatty Alcohols
High-molecular-weight alcohols like Cetyl, Stearyl, and Cetearyl alcohols are typically derived from fatty acids in plant oils such as coconut or palm oils – hence the name “fatty alcohols.” Fatty alcohols are thick, waxy, and often solid at room temperature. Rich in healthy fats and used as emulsifiers, emollients and thickeners, they create thick, creamy textures in skin care products. To most, fatty alcohols are not irritating and nothing to worry about.
Fatty alcohols can also be obtained from animal fats. Now produced from coconut or palm oil, and also known as Palmityl alcohol, Cetyl alcohol was originally produced from whale oil, from which it got its name – cetus means whale oil in Latin. Lanolin, commonly found in skin and lip balms, is a fatty alcohol obtained from sheep wool. Oleyl Alcohol is typically derived from olive oil, but may also originate in beef fat or fish oil.
Cetyl, Stearyl, and Cetearyl alcohol: what’s the difference?
The answer is… there isn’t much. The molecular structure of Cetyl alcohol is very similar to that of Stearyl alcohol, which is longer by just two carbon atoms. The latter is slightly heavier and thicker, but both essentially share the same properties as emollients, emulsifiers, thickeners, and surfactants. Cetearyl alcohol is nothing but a mixture of Cetyl and Stearyl alcohol!
Other fatty alcohols
Similar to Stearyl and Cetyl alcohol, Lauryl alcohol, aka Dodecanol, is sometimes selected for its distinct aroma.
Behenyl alcohol (aka Docosanol) is typically derived from corn, rapeseed and other vegetable oils. Used as a viscosity agent, it also has a comparatively high melting point and antiviral properties. It appears for instance in some lip care stick products.
Myristyl alcohol is a distinctly lighter heavy-weight derived from coconut and palm oil but also from nutmeg, which gave it its name. (Myristica fragrans is the sciency name for nutmeg plant.)
Isostearyl alcohol and Oleyl alcohol, aka Octadecanol, are also on the lighter side – unlike most other fatty alcohols, they are liquid at room temperature which makes them thinner and less occlusive.
Alcohols are not universal bogeymen. Low molecular weight alcohols are best avoided to avoid dryness, redness, and a weakened skin barrier. Fatty alcohols are generally safe, unless you have a specific allergy or sensitivity.
The trick is to remember that ethyl alcohol is one but cetyl alcohol is the other. Here’s a cheat sheet!