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Despite the fact that experts generally consider the versatile ingredient propylene glycol to be safe when used in skincare, you can't overlook the fact that it was named the American Contact Dermatitis Society's Allergen of the Year in 2018 due to its bad rap for causing contact dermatitis. If you're one of the lucky ones who experiences adverse reactions to the ingredient, like redness or itchiness, or if you're someone with eczema who could be particularly sensitive to it, you're likely on the hunt for a less irritating alternative to propylene glycol that's safer for your skin. One sub worth mentioning: propanediol.
Although the two are very similar, there are some key distinctions that could make propanediol a better option for you. To find out exactly what these differences and similarities are as well as other important characteristics to note, we interviewed board-certified dermatologist Sapna Palep, MD, of Spring Street Dermatology in NYC, and cosmetic chemist Michelle Wong, PhD, and content creator at Lab Muffin Beauty Science. Together, they explain everything you need to know before making the switch from propylene glycol to propanediol in your skincare. Keep scrolling to read all about what they have to say about the ingredients.
Type of ingredient: Solvent, humectant, and emollient.
Main benefits: Dissolves ingredients, decreases viscosity, and retains moisture.
Who should use it: Generally, anyone looking for an alternative to propylene glycol in their skincare.
How often can you use it: Propanediol is a safe ingredient to use regularly, provided that you do not have a sensitivity to it.
Works well with: Because of its wide range of uses, propanediol does not function especially well with any ingredient in particular.
Don't use with: According to dermatologists, ropanediol works well with most, if not all, ingredients.
What Is Propanediol?
Technically speaking, propanediol is a three-carbon diol and a colorless viscous liquid that is miscible (or mixible) with water. Since it's derived from corn sugar, Palep describes propanediol as a natural alternative to propylene glycol. It can be found in cosmetics and personal care products, like lotions, cleansers, toners, and other topical skin treatments. A bit of an overachiever, propanediol can function as a solvent, humectant, and even an emollient when used in skincare.
Benefits of Propanediol for Skin
The reason you can spot propanediol on so many different product labels is due to its versatility. Although Palep says it primarily functions as a solvent, propanediol also has impressive sensory qualities and various other benefits when used in skincare.
- Dissolves ingredients: According to Palep, propanediol is considered to be an excellent solvent for harder to dissolve ingredients, like salicylic acid or ferulic acid, for instance.
- Decreases viscosity: As Palep explains it, a viscosity reducer is helpful in a variety of cosmetics, like conditioner, shampoo, foundation, mascara, body wash, hair spray, cleanser, and moisturizer, because it allows the formulas to flow well and makes them easier to use on the skin and hair.
- Improves humectancy: As a humectant hair and skin conditioner, propanediol pulls moisture into the skin and encourages water retention.
- Prevents water loss: Thanks to its emollient properties, propanediol softens and smooths skin by reducing water loss.
- Safe for acne-prone skin: According to Palep, foam cleansers tend to use fewer surfactants (the cleansing chemicals that remove dirt and oil from your skin), which makes them ideal for acne-prone or sensitive skin types. Propanediol can increase foaming in a product, so those prone to breakouts might prefer products containing the ingredient for that reason.
- Enhances preservative efficacy: Palep adds that propanediol can also function as a preservative booster in skincare products.
- Gives the product a lightweight feel: Not only does propanediol contribute to the function of a product but also its consistency. Palep says the ingredient gives products a light texture and a non-sticky feel.
Propanediol vs. Propylene Glycol
It's easy to see how 1,2-Propanediol and 1,3-Propanediol (aka propylene glycol and propanediol, respectively) could be regularly confused for each other. The two ingredients are very similar and even share the same chemical formula; however, they have different chemical structures (as Wong explains it, the alcohol group is connected differently), which changes the way they function.
But structurally isn't the only way the ingredients differ. Palep adds that propanediol is derived from corn, while propylene glycol is derived from petrochemicals. Although propylene glycol is determined to be safe in skincare and cosmetics, propanediol is commonly used as an alternative to propylene glycol for those who want products that don't contain petroleum-based glycols. Palep points out that not enough studies exist yet to determine if it's the safer option, but studies show propanediol to be less sensitizing and irritating to the skin than propylene glycol.
Side Effects of Propanediol
Generally, propanediol is safe to use in skincare products for those who do not have an allergy to it. When using a new product, always patch test on a small area of the skin before applying all over your body. Palep says although there could be a small risk of irritation for some, there are no serious side effects.
How to Use It
Because propanediol has many different uses and is included in a wide variety of formulas, how it should be applied largely depends on the specific product, so use as directed by your dermatologist. But Wong adds that unless your skin is sensitive to it, propanediol is safe to incorporate into your skincare routine on a daily basis.
The Best Products With Propanediol
If you've never heard of CoQ10, you're not alone. It's not exactly the most talk-about ingredient, but once you discover all its skin-loving benefits, you'll be singing its praises to anyone who will listen. Commonly used in Japanese beauty, CoQ10 is an antioxidant that hydrates, evens, and, of course, neutralizes free radicals. This Byrdie editor-recommended toner combines those benefits with the humectant properties of propanediol and the soothing properties of aloe and chamomile to hydrate and rejuvenate the skin.
The biggest misconception about acne is that you need to wash your face with harsh soaps to strip away all the excess oil, bacteria, and debris in your pores. In reality, acneic skin needs a much gentler formula to help steady the oil production and soothe the irritation. Enter: this gentle foam cleanser that comes highly recommended by Byrdie's editors. Thanks to propanediol, this foaming face wash uses fewer surfactants (harsh cleansing chemicals) and is able to remove even the toughest long-wear makeup without stripping the skin.
Oily and acne-prone skin types, listen up. This mattifying formula, which transforms from a gel into a toner as it's applied, will tackle your biggest skin concerns: visible pores, excess oil, and redness. Chock full of all the best ingredients, like bentonite clay, cucumber, green tea, witch hazel, and marshmallow extracts, as well as propanediol, this Byrdie editor-recommended product feels lightweight on the skin and is perfect for layering under makeup. If your foundation or concealer tends to break up throughout the day because of your oily T-zone, the toner can also be used to set your face makeup and lock it in place all day.
A refreshing face mist that protects against environmental aggressors, hydrates, and plumps? Yes, please. With a powerful blend of antioxidants, peptides, and, of course, the multitasking ingredient propanediol, no wonder it's a Byrdie editor top pick for protecting the skin against pollution. As a multifunctional product, you can use it in your skincare routine, and also to prep your face for makeup application or afterward as a fixing spray.
Covering active acne breakouts is a battle. Thankfully, this tinted acne spot treatment, which is beloved by Byrdie's editors, covers while it treats the skin so you don't have to worry about exacerbating the issue with makeup. Formulated with a blend of impurity-fighting ingredients—including tea tree oil and bioflavonoids—this spot treatment truly multitasks. It also has a smooth flowing texture, lightweight feel, and for that, you can credit propanediol.
Loaded with powerful ingredients like salicylic acid, a blend of AHAs, and fruit extracts, this exfoliating night serum gets help from propanediol to dissolve the ingredients, decrease the viscosity and give the formula a lightweight, non-sticky feel. With 160k loves on Sephora and equal praise from Byrdie editors, this blackhead-fighting serum does everything from unclogging pores, to evening skin tone and rough texture.
If dullness, dryness, and an uneven skin tone or texture are your biggest skin concerns, try this moisturizer for a little daytime pick-me-up. Thanks to ingredients like sodium hyaluronate and a trio of powerful vitamin C sources, this lightweight gel formula not only brightens complexions but also hydrates and plumps the skin. And with help from the solvent propanediol, the hard-to-dissolve ingredients, like ascorbic acid, are easily incorporated into the formula. No wonder it's one of Byrdie's favorite vitamin C-infused products on the market.