Polybutene: Your Guide To The Skincare Ingredient You're Probably Already Using

Skincare and cosmetics are a pervasive part of adult life. According to estimates from the Environmental Working Group, one in every 100 men and more than one-quarter of women use at least 15 personal care items every day. A typical adult uses up to nine personal care products each day, exposing their face to 126 different chemical components. But even though we expose our skin to lots of chemical ingredients, many of us can't identify half the names on the ingredient list (save for the hero ingredients that really matter to our skin). 

In a skincare product, there are only a couple of game-changing ingredients. The rest are usually placeholders, such as thickeners, emulsifiers, fragrances, pH stabilizers, and colors. Polybutene is one of them. If you go through the labels of all your makeup and skincare products, there's a chance you'll find polybutene at least once in the ingredient lists.

Polybutene, which is frequently included in lipstick, mascara, and foundation, is crucial to the chemistry that enables all of the elements to come together to produce a cohesive physical product. Here's what to know about polybutene and the role it plays in our skincare products.

According to Paula's Choice, polybutene is a colorless synthetic liquid that is used in cosmetics as a binder and a thickening agent. An organic polymer, polybutene is typically composed of the chemical compounds 1-butene, 2-butene, and isobutylene. The resulting chemical's large size prevents it from penetrating past the topmost layers of skin, which makes it a perfect ingredient to bind and thicken makeup and skincare products. 

As a thickening agent, polybutene can boost a liquid's viscosity without significantly altering its other qualities, giving it a desirable consistency. As a binder, polybutene serves to bind different components together to form a cohesive combination and maintain texture throughout usage. Due to its naturally adhesive nature, polybutene is commonly used in many oils, eye makeup, lip makeup, and hair care products.

Furthermore, polybutene tends to be non-sensitizing and non-comedogenic, which means it is generally safe to use for most people, dermatologist Carmen Castilla told Byrdie. Carbomer, cetyl palmitate, and ammonium acryloyldimethyltaurate are some examples of other synthetic thickeners used in cosmetics.

Aside from thickening a product and holding its different ingredients together, polybutene also serves as an emollient, a component that coats the skin with a protective layer to trap moisture. For this reason, polybutene is found in many moisturizers where it serves to boost the thickness of the lipids to make your skin feel smoother and softer, Dr. Carmen Castilla explains. However, keep in mind that polybutene by itself has no direct benefits for the skin. Furthermore, polybutene has a low odor and is completely transparent, so it is unlikely to alter the appearance or smell of a product.

Don't be surprised if you find polybutene in a waxing product. Polybutene is also an epilating agent — a sticky, wax-like substance that can be applied to the skin to strip off unwanted hair.

Thanks to its thickening properties, polybutene is also the unsung hero behind the glossy and rich finish of your lip gloss. In fact, you can use polybutene to DIY your own lip gloss. According to Humblebee & Me, you can create your own nourishing lip oil by mixing polybutene with a liquid oil of your choice.

In terms of potential side effects, polybutene has relatively low acute toxicity, according to The United States Environmental Protection Agency (EPA). Although not harmful to the skin, polybutene doesn't bode well for the eyes and has been classified in Toxicity Category II for its irritating effect, according to the EPA.

The Cosmetic Ingredient Review (CIR) published in the International Journal of Toxicology also rates polybutene as safe to use in cosmetics and notes that it doesn't pose any risks when used at a concentration of 4% or less. Since polybutene doesn't clog pores and is too large to worm its way under the skin, it can be used throughout the day without inflicting any irritation on the skin. As a skincare ingredient, polybutene is safe to use with most ingredients and is not a cause for concern.

In terms of its ecological impact, polybutene doesn't pose any risks to the environment and aquatic organisms, according to FloPlast. As a highly stable polymer, polybutene is resistant to physical and chemical impacts caused by aging or temperature changes.

Aside from polybutene, there are many polymers that have been used as cosmetics thickeners, such as xanthan gum, acacia gum, hyaluronic acid, and hydroxyethyl cellulose.

Xanthan gum is one of the most popular thickeners in skincare products. Not only is it harmonious with many other ingredients, but it's also packed with conditioning properties that hydrate and smooth skin. "It's formed when sugars are fermented with a bacteria known as Xanthomonas campestris to create a goo-like substance," dermatologist Stacey Steinmentz told Byrdie. Acacia gum, a derivative of the Acacia tree, is also an effective natural thickener that's often paired with xanthan gum in cosmetics.

Hyaluronic acid, a famous moisture preserver and the hero ingredient in many moisturizers and serums, is also capable of boosting a formula's viscosity in addition to enhancing the skin's water content, per Humblebee & Me.

Derived from cellulose, hydroxyethyl cellulose is a polymer that's frequently used in personal care products and cosmetics as a thickener to create formulas with gel-like textures such as shampoos, facial cleansing cream, lotion, and shower gels, according to LeCerre.

Although thickening or binding agents are usually the least of our concerns when buying personal care products, it pays to get to know more about them and double-check their impact on our skin health.