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"Alcohol Denat." is one of the most common ingredients in perfumes, toners, hairsprays, and hand sanitizers. It's also one of the most misunderstood. It isn't a special type of alcohol. It's regular ethanol with a small amount of an additive mixed in so it can't be used as a drink.
That small addition matters more than it sounds. It changes how the ethanol is taxed in the US, who is allowed to buy it, and what it can be used for. For brands and labs sourcing ethanol, knowing the difference between denatured and undenatured alcohol affects cost, labeling, and compliance.
Below, we explain what denaturing is, how the two types compare, and how to choose the right one for your product.
What Is Undenatured Ethanol?
Undenatured ethanol is pure ethyl alcohol with nothing added to it. At high purity, such as 99.5%, it's close to water-free and chemically very clean. In the US it's sometimes called "potable" alcohol, because in principle it's the same substance used in alcoholic drinks.
That's what makes it tricky to sell. The government treats undenatured ethanol as beverage alcohol, so it carries federal excise tax unless the buyer holds a permit for tax-free use. Hospitals, universities, and research labs often have those permits. Most small businesses don't.
On a cosmetic ingredient list, undenatured ethanol usually just appears as "Alcohol."
What Is Denatured Ethanol?
Denatured ethanol is ethanol mixed with one or more additives, called denaturants, that make it unpleasant or unsafe to drink. The ethanol itself doesn't change. It still dissolves ingredients, evaporates quickly, and feels light on the skin. It just can't be passed off as a drink.
Because it can't be consumed, denatured alcohol isn't taxed like beverage alcohol. That makes it much more affordable, and it's the main reason it dominates personal care manufacturing.
Common denaturants include:
- Denatonium benzoate, one of the most bitter substances known. A tiny amount makes alcohol taste terrible.
- Tert-butyl alcohol, another alcohol often used alongside denatonium benzoate.
- Isopropyl alcohol, used in some formulas.
- Methanol, used in certain industrial formulas, but not suitable for products that go on skin.
On a label, denatured ethanol shows up as "Alcohol Denat.", the international cosmetic ingredient (INCI) name. Some US products instead list the specific formula, such as "SD Alcohol 40-B."
Specially Denatured vs Completely Denatured Alcohol
In the US, denatured alcohol is regulated by the Alcohol and Tobacco Tax and Trade Bureau (TTB), which approves specific denaturing formulas. They fall into two groups.
Completely denatured alcohol (CDA) contains denaturants that make it unsuitable for almost anything except industrial use. Think fuels, solvents, and cleaning. You don't need a permit to buy it, but it doesn't belong in cosmetics.
Specially denatured alcohol (SDA) is made for particular uses, including personal care products. The additives are chosen to keep the ethanol useful for formulating while still making it undrinkable. Businesses using SDA generally need a TTB permit and must follow the approved uses for their formula.
SDA 40-B is the one you'll see most often in beauty. It's denatured with denatonium benzoate and tert-butyl alcohol, and it's a standard choice for perfumes, toners, hair sprays, and aftershaves.
Denatured vs Undenatured Ethanol at a Glance
| Undenatured Ethanol | Denatured Ethanol | |
|---|---|---|
| What it is | Pure ethyl alcohol | Ethyl alcohol plus approved denaturants |
| Label name | Alcohol | Alcohol Denat. / SD Alcohol 40-B |
| Drinkable? | Chemically yes, at proper dilution | No |
| Tax | Federal excise tax unless permit-exempt | Not taxed as beverage alcohol |
| Cost | Higher | Lower |
| Common uses | Food flavorings, some pharmaceuticals, sensitive lab work | Cosmetics, fragrance, sanitizers, cleaning |
Where Each Type Is Used
Denatured ethanol is the standard for:
- Perfumes, body mists, and colognes (see our guide to ethyl alcohol in perfume making)
- Toners and astringents
- Hairsprays, dry shampoos, and styling sprays
- Hand sanitizers
- Aftershaves and deodorant sprays
- Surface and equipment cleaning
Undenatured ethanol is usually chosen for:
- Food flavorings and extracts
- Some pharmaceutical and medicinal preparations
- Laboratory work where denaturants could interfere with results, such as analytical testing
- Products that go on or near the lips, where a bitter denaturant would be noticeable
Is "Alcohol Denat." Bad for Your Skin?
This is the question most people are really asking, and the honest answer is that denaturing isn't the issue.
Any drying effect from alcohol in skincare comes from the ethanol itself, and it depends on how much is in the formula and what else is in there with it. A toner with a high alcohol content and nothing to replace moisture can leave skin tight. A serum that uses a small amount of alcohol to help ingredients absorb, balanced with glycerin or other humectants, is a very different product.
The denaturants in cosmetic-grade SDA formulas are present in very small amounts. They're there to stop people from drinking the product, not to change how it acts on skin.
If you want the bigger picture, our guide on alcohol in skincare explains how ethanol differs from fatty alcohols like cetyl and stearyl alcohol, which are actually moisturizing. For hair, see Is Ethyl Alcohol Always Harmful to Curly Hair?
How to Choose the Right One for Your Brand or Lab
If you're formulating or sourcing ethanol, ask these questions:
1. What is the end product? Leave-on skincare, fragrance, and haircare almost always use SDA. Food, oral, and certain lab applications may need undenatured ethanol.
2. Could the denaturant affect the formula? A bitter agent won't matter in a hairspray but could matter in a lip product. In lab settings, even tiny amounts of an additive can throw off sensitive tests.
3. What permits do you have? Using SDA generally requires a TTB permit, and tax-free undenatured ethanol requires one too. Check your regulatory obligations before you place a bulk order.
4. What does your label need to say? "Alcohol" and "Alcohol Denat." aren't interchangeable. Your ingredient list must match what's actually in the bottle.
5. Can your supplier prove what you're getting? Ask for a Certificate of Analysis (COA) and Safety Data Sheet (SDS) for every batch. Purity, water content, and any denaturant should be clearly stated.
For more on how ethanol behaves in formulas, read Ethyl Alcohol 99.5% in Cosmetics: Uses, Benefits & Formulation Insights.
The Bottom Line
"Alcohol Denat." isn't a mystery chemical. It's ethanol that's been made undrinkable so it can be used affordably in the products people use every day. Undenatured ethanol does the same job chemically, but it costs more and comes with more paperwork, so it's usually reserved for uses where purity or consumption rules require it.
Which one you choose depends on what you're making, what your label needs to say, and what your permits allow.
Natural Cosmetic Labs supplies high-purity Ethyl Alcohol 99.5% for cosmetic, laboratory, and industrial use, with documentation available on request. Contact our team if you have questions about which grade suits your application.
Frequently Asked Questions
Q. Is denatured alcohol the same as ethanol?
Yes. Denatured alcohol is ethanol with small amounts of additives that make it undrinkable. The ethanol itself is chemically unchanged.
Q. What does "Alcohol Denat." mean on a cosmetic label?
It means the product contains denatured ethanol. It's the standard ingredient name used on cosmetic labels worldwide.
Q. What is SD Alcohol 40-B?
It's a specially denatured alcohol formula approved in the US for personal care products. It's denatured with denatonium benzoate and tert-butyl alcohol and is widely used in perfumes, toners, and hair products.
