A common myth about hair care products is that alcohols are bad for your hair. But should you really be worried about finding an appropriate alcohol free shampoo for your hair? Not necessarily.
Not all the alcohols and alcoholic ingredients used in shampoos are bad for your hair. Some of the alcohols are vital for shampoos and some of them are really beneficial to your hair. If you know about the function of different types of alcohol and identify the ones that are bad for your hair then you don’t have to worry about the alcohol content in your shampoos.
The function of alcohols in shampoos
Alcohol is the common name for substances of –OH (hydroxyl) group. Often you’d recognize them in the shampoo ingredients list, as their name mostly ends “-ol”. Alcohols and alcoholic substances used in shampoos and other hair care products can be divided into two main groups.
- Short-chain alcohols
- Fatty alcohols
Alcohols from both of these groups have different functions and different effects on your hair.
Short- chain alcohols and their functions
These groups of alcohols have only a 2-3 carbon atoms in the main chain. In the labels of shampoos short chain alcohols might be listed as –
- Ethanol or ethyl alcohol or pure alcohol (a chain of two carbon atoms, very soluble in water)
- SD alcohol or Alcohol Denat – Specially denatured (SD) alcohol is a mixture of ethanol with a denaturing agent. This is done to render the alcohol unsuitable for drinking, and hence, this is the main form of alcohol found in cosmetics.
- SD alcohol 40 – ethanol mixed with tert-butyl alcohol. Authorized for use in shampoos and other hair care products by the FDA.
- Propanol, Propyl alcohol, Isopropyl alcohol, or Isopropanol (a chain of 3 carbon atoms, less soluble than ethanol.
Due to their short tails these alcohols are slightly soluble in water and can dissolve other ingredients such as oil which do not dissolve in water. These alcohols are mainly used in shampoos as solvents. In addition, these alcohols also function to decrease viscosity of the shampoo and are astringents, meaning, they cause contraction of the scalp skin.
Short chain alcohols have less molecular weight and therefore they can evaporate quickly. For this property short chain alcohols are sometimes used in hair sprays and shampoos to shorten the time for hair drying.
Short chain alcohols are irritating to eyes and upper respiratory tract even in low concentrations, and hence it is suggested to avoid them in your personal care products.
Fatty alcohols and their functions
Fatty alcohols are mostly extracted from different natural sources and they have longer carbon chain consisting of at least 12 carbon atoms in the main chain. Some fatty alcohols that are frequently used in shampoos are-
- Lauryl alcohol – 12 carbon atoms, saturated.
- Stearyl alcohol – 18 carbon atoms, saturated.
- Cetyl alcohol – 16 carbon atoms, mono-unsaturated.
- Cetearyl alcohol – a blend of stearyl alcohol and cetearyl alcohol.
- Myristyl alcohol – 14 carbons atoms.
- Behenyl alcohol – 22 carbon atoms.
The group name of these alcohols suggests that they are related to fats and oils. Thanks to the higher number of carbons in the main chain, these alcohols are used as moisturizers in shampoos and conditioners, as well as an emulsifier to improve mixing oily ingredients with water based ingredients in the shampoo mixture. The oily content of these alcohols help in keeping the cuticles of hair strands closed and preserving the natural oil and moisture of hair evaporating.
Fatty alcohols are also used as emulsion stabilizers, thickeners and as nonionic surfactants. As surfactants, they are very mild cleaning agents. When used as the only cleaning agent in a shampoo (such as in WEN conditioning cleanser products), they will not form any foam when cleaning. Since fatty alcohols are cheaper than other thickeners and emulsion stabilizers, sometimes you can find shampoos with fatty alcohol contents as high as 4-5%.
Among other alcohols used in shampoos Benzyl alcohol and Propylene Glycol are notable. Benzyl alcohol is used as a preserving ingredient in shampoos. It is a neutral alcohol and doesn’t have any effect on your hair. Propylene Glycol is a hydrophilic substance (water-soluble) and humectant, which means, it can attract water and help in preserving the moisture of hair.
Final verdict: Opt for a short chain alcohol free shampoo when possible
Alcohol free shampoo, is probably not necessary, however, a few of the more “natural” shampoos on the market probably are “alcohol-free” altogether. From the discussion above, it is clear that fatty alcohols are moisturizing and conditioning agents, beneficial to the hair and scalp. So shampoos containing fatty alcohols are actually helpful for your hair. They are generally safe to use and have no known adverse effect on the skin.
On the other hand, shampoos containing short chain alcohols such as Ethanol and SD alcohols could cause irritation of eyes, skin and even respiratory system. When possible, it is highly recommended to avoid these ingredients in your cosmetics.
Since different alcohols have different but important functions, it would be very tough to find a shampoo that does not contain alcohols or alcoholic ingredients at all. However, some alcohols are actually beneficial and using a shampoo that contains long-chain alcohols should not pose any health concern.
Most of the sulfate-free shampoos recommended on this site, certainly do not contain short chain alcohol. You can start exploring these products here.