Alcohol denat is an abbreviation for denatured alcohol, which is used in cosmetics and personal care products as an anti-foaming agent, astringent, antimicrobial agent, and a solvent.
Denatured alcohol is ethanol (also called ethyl alcohol) that contains a denaturant to make it taste bad. This is done because ethanol is the alcohol found in alcoholic beverages such as liquor, wine, beer, etc. In the United States, alcoholic beverages are heavily taxed. According to Cosmetics Info, in order to avoid paying beverage taxes on alcohol that is not meant to be consumed (i.e. for use in cosmetic and personal care products), the alcohol must be denatured per specific formulations given by the U.S. Government’s Alcohol and Tobacco Tax and Trade Bureau (TTB). The process adds a small amount of a denaturant to the alcohol to make it taste bad, thus creating alcohol that is not suitable for drinking, but is otherwise similar for other purposes.
Due to the diversity of industrial uses for denatured alcohol, hundreds of additives and denaturing methods have been used. Common denaturants in cosmetics and personal care products include denatonium benzoate, t-butyl alcohol, diethyl phthalate, and methyl alcohol. The process of denaturing alcohol does not chemically alter the ethanol molecule.
Denatured alcohol is generally identified as Alcohol Denat or SD (specially denatured) Alcohol on a product’s ingredient label.
Denatured alcohol has a variety of functions in cosmetics and personal care products, including as an anti-foaming agent, astringent, antimicrobial agent, and a solvent.
One of the primary functions of denatured alcohol is as an astringent. An astringent is a substance that causes biological tissue to contract or draw together. After topical application, astringents work on the protein keratin found in the skin. Keratins function to hold skin cells together to form a barrier. The bonds between keratins are affected by temperature and pH, forming only when skin is slightly acidic or cool. If the bonds break, the keratin molecules will separate, causing the outer layer of skin to swell. Astringents cool the skin and cause the bonds to reform. It is this process that produces the temporary toning effect associated with astringents.
Denatured alcohol is frequently used in products designed to treat acne. According to skin care expert Paula Begoun, this is because denatured alcohol can give products a quick-drying finish, immediately degrease skin, and feel weightless on skin. These properties may sound very appealing if you have an oily skin type. However, the immediate de-greasing effects of alcohol-based products can actually stimulate the sebaceous glands to produce more oil, causing skin to look even more shiny and oily than it was before. This excessive oil production combined with the possible irritation that denatured alcohol can cause may lead to an increase in acne breakouts.
The Cosmetic Ingredient Review Expert Panel (CIR) concluded that safety of ingredients containing denatured alcohol should be predicated on the safety of the denaturants used since dermal application or inhalation of cosmetic products containing these ingredients will not produce significant systemic exposure to ethanol. The Panel considered that the adverse effects known to be associated with alcohol ingestion do not suggest a concern for Alcohol Denat. or SD Alcohols because of the presence of the denaturants. The safety of the alcohol denaturants Denatonium Benzoate, t-Butyl Alcohol, Diethyl Phthalate, and Methyl Alcohol were reviewed by the CIR Expert Panel in 2008 and found to be safe as used.
Despite the approval of denatured alcohol by the CIR Expert Panel, the safety of this ingredient in skin care products is controversial. When high concentrations of denatured alcohol are used in the formulation of skin care products, this ingredient can cause drying and irritation. Denatured alcohol can also cause erosion of the skin’s surface layer, leading to a weakened skin barrier. However, according to FutureDerm, if lower concentrations of denatured alcohol are used, this ingredient may simply be acting as a degreasing agent, making for a better texture of the skin care formulation.
Ultimately the safety of Alcohol Denat. in cosmetics and personal care products depends on both the type of denaturant and also the concentration that is used to create the formulation.
References: Cosmetics Info, “Alcohol Denat”, Wikipedia, “Denatured Alcohol”, The Naked Chemist, “Astringent products, their role on the skin”, 2015, Paula’s Choice, “Alcohol in Skincare: The Facts”, Int J Toxicol. 2008;27 Suppl 1:1-43, FutureDerm, “The Most Misunderstood Skincare Ingredient: Alcohol”, 2007.