What does "denat" actually mean?

Denat is short for denatured. A denaturant is added to prevent cosmetic alcohol from being diverted for drinking. "Alcohol Denat." is a generic ingredient name introduced in Europe and also used on products sold internationally. You can also see "SD Alcohol", meaning specially denatured alcohol, with numbers or letters identifying how it was denatured. Some labels print both naming formats together, apparently in case one name was too straightforward. "Alcohol" on its own refers to ethyl alcohol in cosmetic labelling; ethanol and ethyl alcohol are names for the same substance.13

Is it the same as cetyl or cetearyl alcohol?

No. Cetyl, stearyl, cetearyl and lanolin alcohol are fatty alcohols, with different effects on skin from ethyl alcohol. Do not treat every ingredient containing the word "alcohol" as alcohol denat. A product labelled "alcohol free" can still contain fatty alcohols. An "alcohol free" claim has a narrower meaning than it sounds, which is a lot of work for two words. If you are trying to avoid denatured ethanol, distinguish its names from fatty alcohol names when checking the ingredient list.1

What does ethanol do on skin?

Ethanol is used as a solvent, meaning it helps dissolve substances. Applied to skin, ethanol also helps other substances pass through the skin. Ethanol use is associated with irritation and contact dermatitis, an inflammatory skin reaction. Its presence is therefore relevant if you are choosing products for easily irritated skin. Long term effects of topical ethanol remain uncertain. The practical distinction is between identifying an ingredient and deciding whether a particular product suits your skin: the words "alcohol denat" answer the first question, not the second.2

Who should be more careful?

If you have rosacea, choose products without alcohol, including alcohol denat. Rosacea often makes skin sensitive and easily irritated. Choose fragrance free products made for sensitive skin, and test new skincare before applying it to your face. Avoid astringents and toners. If you struggle to find products that do not irritate your skin, ask your dermatologist for specific options. If you use medication for rosacea, apply the medication before a suitable moisturiser. That is general rosacea care, not a reason to change a prescribed treatment because of one ingredient name.4

What if a product stings or causes a rash?

Stop using a product that causes a skin reaction. Burning, itching, scaling, redness, swelling or blisters can be signs of a cosmetic reaction. Irritation from a strong irritant can appear within minutes or hours; weaker irritants can cause symptoms after days or weeks of repeated exposure. An allergic rash usually develops more than 12 hours after contact and peaks around 48 hours. A reaction does not identify alcohol denat as the culprit: any cosmetic ingredient can cause a contact reaction, and fragrances and preservatives are common causes. A cosmetic allergy can also develop after years of previously trouble free use. For recurring reactions, a dermatologist can use patch testing to investigate possible allergens rather than guessing from the label.5

Where this answer comes from

  1. 1"Alcohol Free"fda.gov
  2. 2Safety evaluation of topical applications of ethanol on the skin and inside the oral cavitypmc.ncbi.nlm.nih.gov
  3. 3UNII - 3K9958V90Mprecision.fda.gov
  4. 47 rosacea skin care tips dermatologists recommendaad.org
  5. 5Cosmetics Allergy: Causes, Symptoms, and Treatmentdermnetnz.org