The discussion surrounding alcohol in skincare is quite similar to the debate on whether oil is good for your skin—everyone just couldn't seem to agree. With alcohol, the argument is that it can dry out your skin—which is true to an extent, but it must be noted that not all alcohols work the same way. Some types of alcohol are actually beneficial for your skincare, and it all boils down to knowing what your skin can tolerate in the long run.
Generally, there are two kinds of alcohols that you'll find in your skincare products: simple alcohols and fatty alcohols.
The "Bad" Alcohols: Simple Alcohols
Simple alcohols include denatured alcohol, ethyl alcohol, and isopropyl alcohol, SD alcohol, and ethanol. Dr. Sharon Crichlow tells Pop Sugar that these tend to dissolve the skin's protective lipids, dehydrating it and damaging your skin in the process—especially in high concentrations. These are considered "bad" alcohols because they dry out your skin and cause issues in the long run.
Putting too much simple alcohols on your skin, for one, will make you produce more oil as a response to the dryness, and overtime, it'll reduce your natural oil production. Before you feel excited, FYI, it's not necessarily a good thing because without your natural oils, you're automatically more prone to irritation and your skin will tend to age faster. Basically, that temporary matte look and tight feeling you get from using that alcohol-rich toner? Not worth it!
That said, these aren't exactly the worst thing to have in your skincare either. Small amounts of simple alcohols in skincare actually help act as a preservative and make products like creams and lotions easier to absorb. Esthetician Renee Rouleau says they aren't so bad in spot treatments either, since alcohol will help dry out a pimple faster. However, if a moisturizer, serum, or toner has a simple alcohol listed as one of the first five (or 10, if you're extra careful) ingredients, you might want to skip it.
The "Good" Alcohols: Fatty Alcohols
If simple alcohols dry out your skin, fatty alcohols do the exact opposite. That's because fatty alcohols are derived from waxes and oils and are actually nourishing for the skin and are used as emulsifiers in products.
Examples of fatty alcohols are cetyl, catearyl, stearyl, myristyl, and lauryl alcohol, as well as propylene glycol—all of which either help emulsify products or retain moisture in the skin. Hence, these won't dry your skin out like simple ones will. The only issue you could encounter with fatty alcohols is that they do tend to make products thicker and more emollient in high amounts. Also, as with all skincare ingredients, it's still possible to be allergic or break out from a product with fatty alcohols—even if it doesn't contain simple ones.
In summary, simple alcohols will dehydrate and cause damage to your skin when used frequently and in high amounts. Fatty alcohols, on the other hand, are potentially moisturizing ingredients that could be beneficial to the skin but could still cause irritation depending on your skin's tolerance. Bottom line: Always check the ingredients list and know what works and doesn't work for you!