What Is Denatured Alcohol?

Denatured Alcohol Composition and Examples

70% isopropyl alcohol is one of the most common formulations of rubbing alcohol.
70% isopropyl alcohol is one of the most common formulations of rubbing alcohol. Brand X Pictures / Getty Images

Denatured Alcohol Definition

Denatured alcohol is ethanol (ethyl alcohol) that has been made unfit for human consumption by adding another chemical to it. Denaturing refers to removing a property from the alcohol (being able to drink it), not to chemically altering or decomposing it.

Denatured Alcohol Chemical Composition

There are hundreds of ways ethanol is denatured. Denatured alcohol that is intended for use as a fuel or solvent typically contains 5% or more methanol.

Methanol is flammable and has a boiling point close to that of ethanol. Methanol is absorbed across the skin and is highly toxic, so you really shouldn't use denatured alcohol for making perfume or bath products. Denatured alcohol for use in cosmetics often contains water and a bittering agent (Bitrex or Aversion which are denatonium benzoate or denatonium saccharide), but other chemicals are sometimes used. Other common additives include (but are not limited to) isopropanol, methyl ethyl ketone, methyl isobutyl ketone, pyridine, benzene, diethyl phthalate, and naphtha.

In some countries, denatured alcohol must be colored blue or purple using an aniline dye, in order to distinguish it from consumption-grade ethanol. In the United States, for example, denatured alcohol need not be colored, so you can't tell whether alcohol is pure or not simply by looking at it.

Examples of Products Containing Denatured Alcohol

Basically, any product that contains ethyl alcohol yet isn't intended for human consumption uses denatured alcohol.

 You'll find denatured alcohol in reagent alcohol for use in labs, hand sanitizer, rubbing alcohol, and fuel for alcohol lamps. It's also found in cosmetics and other personal care products.

What Happens If You Drink Denatured Alcohol?

Short answer: nothing good! In addition to the effects from the alcohol, you'd experience effects from the other chemicals in the mixture.

The exact nature of the effects depends on the denaturing agent. If methanol is the agent, possible effects include nervous system and other organ damage, increased risk of cancer, and possibly death. Other denaturing agents carry risks, plus many products also contain perfumes and dyes not intended for human consumption. Some of these toxic compounds can be removed by distilling the alcohol, but others have boiling points close enough to ethanol that it's unlikely an inexperienced distiller could remove them to the point where the product would be safe for human consumption. However, distillation of a fragrance-free, dye-free product might be a viable option if alcohol is to be used for laboratory situations.

Why Is Alcohol Denatured?

Why take a pure product and make it toxic? Basically, it's because alcohol is regulated and taxed by many governments. Pure alcohol, if it was used in household products, would offer a much less expensive and readily available source of ethanol for drinking. If alcohol wasn't denatured, people would drink it.

Now that you know about denatured alcohol, you may be interested in learning about the ingredients in rubbing alcohol or how you can purify alcohol yourself using the simple process of distillation.