Cetearyl alcohol is a fatty alcohol used as an emollient, emulsion stabilizer, surfactant, opacifying agent, and a viscosity-increasing agent in cosmetics and personal care products.
Cetearyl alcohol, also referred to as cetostearyl alcohol, is a mixture of fatty alcohols, primarily cetyl and stearyl alcohols. Cetyl alcohol is derived from palm oil and stearyl alcohol is derived from stearic acid, a saturated fatty acid. Technical grade cetearyl alcohol contains approximately 65% to 80% stearyl and 20% to 35% cetyl alcohols. Cetearyl alcohol is a white, waxy solid, usually in flake form. It is insoluble in water and soluble in alcohol and oils.
Cetearyl alcohol has many functions in cosmetics and skin care products, including use as an emollient, emulsion stabilizer, surfactant, opacifying agent, and a viscosity-increasing agent.
Cetearyl alcohol imparts an emollient feel to the skin. Emollients are also occlusive agents, which provide a layer of protection that helps prevent water loss from the skin. Thus, cetearyl alcohol has the ability to soften and smooth the skin, which helps to reduce rough, flaky skin. Additionally, cetearyl alcohol is commonly used in hair conditioners and other hair products due to its emollient properties.
Another function of cetearyl alcohol is as an emulsifier. An emulsifier is needed for products that contain both water and oil components. According to EFEMA, when water and oil are mixed together and vigorously shaken, a dispersion of oil droplets in water – and vice versa – is formed. When shaking stops, however, the two phases start to separate. To address this problem, an emulsifier like cetearyl alcohol can be added to the system. This helps the droplets remain dispersed and produces a stable emulsion.
As an emulsifier, cetearyl alcohol consists of a water-loving hydrophilic head and an oil-loving hydrophobic tail. The hydrophilic head is directed to the aqueous phase and the hydrophobic tail to the oil phase. Cetearyl alcohol reduces the surface tension by positioning itself at the oil/water or air/water interface, which has a stabilizing effect on the emulsion. Cetearyl alcohol can be used in water-in-oil emulsions, oil-in-water emulsions, and anhydrous formulations.
Cetearyl alcohol also functions as a surfactant. Surfactant is the short term for surface active agent. Surfactants are compounds that lower the surface tension between two substances, such as two liquids or a liquid and a solid. Another job of surfactants is to degrease and emulsify oils and fats and suspend soil, allowing them to be washed away. This is possible because while one end of the surfactant molecule is attracted to water, the other end is attracted to oil. Thus, surfactants attract the oil, dirt, and other impurities that have accumulated on your skin during the day and wash them away. Due to these properties, cetearyl alcohol can be found in many different cleansers and body washes. Cetearyl alcohol also increases the foaming capacity of non-aqueous (i.e. lotions) and aqueous solutions (i.e. shampoo).
The last important function of cetearyl alcohol is as a viscosity-increasing agent. The term viscosity corresponds to the concept of “thickness”, for example, honey has a higher viscosity than water. As a viscosity-increasing agent, cetearyl alcohol works to thicken formulations in order to make a product less runny and easier to spread.
The Food and Drug Administration (FDA) includes cetearyl alcohol on its list of permitted food additives. The Cosmetic Ingredient Review (CIR) Expert Panel evaluated the scientific data on cetearyl alcohol and concluded that this ingredient is non-sensitizing, non-toxic, and safe to use in cosmetic products.
According to EWG, cetearyl alcohol is rated as a 1 on a scale of 1 to 10, with 1 being the lowest risk to health and 10 being the highest.
Due to its name, cetearyl alcohol is often misunderstood to be bad for the skin since it is an alcohol. It is true that some alcohols, like ethyl or rubbing alcohol, can be extremely drying to the skin. However, quite the opposite is true for cetearyl alcohol, which is well known to effectively condition and soften the skin and hair.
References: Wikipedia, “Cetostearyl alcohol”, Cosmetics Info, “Cetearyl alcohol”, EFEMA, “What is an emulsifier?”, Paula’s Choice, “Surfactant”, Dermcast.tv. “Understanding the Difference Between an Emollient, Moisturizer, and a Humectant”, J Am Coll Toxicol. 1988 Nov. 7(3), EWG’s Skin Deep Cosmetic Database, “Cetearyl Alcohol”.