WTF?! There’s anti-freeze in my moisturizer?! That’s the first thing that comes up when you Google Propylene Glycol. Other worrying results include “toxic”, “carcinogenic,” and “dangerous”. It’s enough to make you wanna toss any skincare products with Propylene Glycol in the bin and write a scathing letter to your congressman.
And yet… Can you really trust everything that auntie Google say? In a world where anyone can write anything online, how can you tell these sources are accurate? It wouldn’t be the first time a nice soul with good intentions misinterprets the science and spreads rumours that don’t tell the whole truth. So who should you believe?
Here at Beautiful with Brains, we’re all about judging skincare ingredients based on science, not fear. At first sight, Propylene Glycol is one of those ingredients that sound scary as hell. But when you look at it through science’s eyes, it’s just a little misunderstood molecule that doesn’t do anyone any harm. Don’t take my word for it. Here’s what science has to say about Propylene Glycol:
- What Is Propylene Glycol?
- Benefits Of Propylene Glycol For Skin: What Does It Do?
- Is Propylene Glycol Safe For Skin?
- How To Use It
- What Are The Best Products With Propylene Glycol?
- The Bottom Line
What Is Propylene Glycol?
Propylene Glycol is a water-soluble liquid without odour or colour. It is made by adding water to propylene oxide, a substance derived from petroleum. That alone is enough for most people to accuse it of the most unspeakable crimes – WITHOUT proof. But, when it’s absorbed by the skin, Propylene Glycol turns into lactic acid – a substance your body naturally produces when it exercises. No danger in that.
Propylene Glycol also belongs to the alcohol family. Another reason why so many people like to hate on it. But not all alcohols are drying for your skin. Propylene Glycol has several functions in skincare products that help skin stay soft and supple. It’s a humectant, an emollient, a solvent, and can even be used as a preservative. With so many tricks up its sleeve, it’s no wonder it’s included in so many skincare products.
Are Propylene Glycol And Dipropylene Glycol The Same?
Propylene Glycol and Dipropylene Glycol are similar, but not the same. Dipropylene Glycol is a colourless, odourless liquid that’s a byproduct made in the production of propylene glycol. In skincare, Dipropylene Glycol is slip agent, texturizer, and solvent that also helps active ingredients better penetrate skin. It’s less irritating than Propylene Glycol, but it’s still a good idea to do a patch test before you use it.
Benefits Of Propylene Glycol For Skin: What Does It Do?
You’ve probably heard that Propylene Glycol is an industrial anti-freeze used in brake and hydraulic fluids. That’s true. So what is it doing in skincare products? FYI, lots of chemicals are multi-taskers that can do completely different jobs, depending on how you use it. At 100% concentrations, it’s an anti-freeze. In the 5% or smaller concentrations used in cosmetics, it has other functions. Let’s look at them one by one:
1. It Hydrates Skin
Propylene Glycol is a humectant. This is a fancy word to describe ingredients that draw moisture from the environment into your skin and bind it there. Moisture is the foundation of healthy skin. It makes skin softer, gives it an as-lit-from-within glow, and even plumps up fine lines and wrinkles, so they look smaller. Propylene Glycol does all this – without the sticky feel that some moisturising oils and butters have. This makes it suitable even for oily, acne-prone skin.
Dr Jennifer Herrmann, MD, FAAD, is a board-certified dermatologist based in Beverly Hill. further adds: “As we age, our skin loses a component called Natural Moisturizing Factor (NMF) and subsequently dries out, which emphasizes wrinkles and contributes to flaking and roughness. Propylene glycol helps bind water from the environment, helping to counter the water loss that accompanies aging.”
Related: What The Heck Are Humectants And Should You Use Them?
2. It prevents Water Loss
As a humectant, Propylene Glycol adds more water into the skin to increase its hydration levels. As an emollient, it also creates a protective barrier on the skin that holds this extra moisture in. When your natural protective barrier is damaged, moisture evaporates, drying out skin and accentuating wrinkles. Propylene Glycol prevents this from happening, so that your skin looks young and healthy.
3. It Enhances The Penetration Of Other Skincare Ingredients
Thanks to its water-binding properties, Propylene Glycol can enhance the delivery of active ingredients into the skin, allowing them to penetrate deeper than they would on their own. When it comes to actives like Vitamin C and retinol, that need to penetrate your skin, this is a positive attribute as it helps them work better and faster. But, it doesn’t help them penetrate your blood stream. Even with its help, skincare ingredients can’t reach that far.
4. Other Uses Of Propylene Glycol For Skin
Propylene Glycol has a couple of other uses. They don’t necessarily benefit skin, but they make your skincare products a pleasure to use:
- Stabilizer: It keeps your lotions from developing a grainy, cottage cheese-like texture when exposed to low temperatures” and from melting at high ones.
- Solvent: It helps dissolve other ingredients in the formula, creating a texture that’s pleasant to use.
- Preservative: It has antimicrobial properties that kill the bacteria that should contaminate your skincare products, helping them last and be safe for longer.
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Is Propylene Glycol Safe For Skin?
Propylene Glycol is derived from petroleum, so a lot of people are concerned it has the same side effects, including causing cancer. But Propylene Glycol isn’t derived from crude oil. It’s derived from cosmetic-grade petrolatum, which is different than commercial petroleum. How? Cosmetic-grade means that ALL toxic and carcinogenic impurities have been REMOVED, making it safe to use on skin.
Can Propylene Glycol Cause Cancer?
No. There is no proof that, in the small concentrations used in skincare products and when topically applied to your skin, Propylene Glycol causes cancer. Dr Hermann explains: “Many safe products and chemicals can be derived from toxic parents, but what matters for safety is the final chemical structure form. Unless contamination is an issue, being derived from petroleum doesn’t make it dangerous. Its final form is considered non-carcinogenic and is found in many topical cosmetic products.”
Is Propylene Glycol Irritating?
But that doesn’t mean Propylene Glycol is completely innocent. Although it won’t give you cancer (phew!), it can cause allergies and red, itchy rashes – especially in people with eczema and very sensitive skin.
Concentration also matters. As an anti-freeze, Propylene Glycol is used at 100% concentrations – and that IS irritating for everyone. In skincare products, it’s usually used around the 2% mark (although it’s sometimes used in higher concentrations as a humectant), so unlikely to cause problems unless you have an allergy to it. Always do a patch test on a small area of your wrist before applying it all over your face – just in case.
Dr Joshua Zeichner, MD, is a board-certified dermatologist and the director of cosmetic research in dermatology at Mount Sinai Medical Center, sums it up best: “Based on what we know today and based on years of use in cosmetic products, propylene glycol is a safe ingredient to use, provided that you do not have an allergy to it.
Related: 7 Skincare Ingredients With An Undeserved Bad Reputation
Is Enhanced Ingredient Penetration Dangerous?
Propylene Glycol may not cause cancer or irritations, but it CAN penetrate skin. Surely, THAT must be dangerous?
Nope. Here’s why:
- Absorption is minimal: Only the tiniest amount of Propylene Glycol penetrates into the skin. It’s the dose that makes the poison – ALWAYS.
- Safe to eat: According to the World Health Organization, ingesting 25 mg of Propylene Glycol per kg body weight every day is fine (you either pee it out or your body breaks down in the blood to form lactic acid, which is naturally produced by your body). You put much less on your skin. (Please, don’t start eating your skincare now!).
The only time when Propylene Glycol is dangerous is when you apply it to open, broken skin. But that’s true for every ingredient. You don’t want to apply anything on broken skin.
What about the other ingredients Propylene Glycol helps to get through the skin? Again, no danger here. Propylene Glycolic is a weak penetration enhancer. It helps skincare ingredients penetrate deeper into your skin, but not so deep to reach the bloodstream.
Related: Does Your Skin Really Absorb 60% Of What You Put On It?
How To Use It
Propylene Glycol is in so many toners, serums, and moisturisers, there’s no just one way to use it. I recommend you read the label of the product you’re using and follow instructions. As a rule, though, products with lighter textures go first and those with heavier textures go last. Also, don’t apply it on broken skin – only on healthy, intact skin.
Who Can Use It?
Unless you’re allergic to it, anyone can use it. Thanks to its humectant properties, Propylene Glycol deeply hydrates oily skin without adding more oil to it and causing breakouts, and quenches the thirst of dry skin, too.
How Often Can You Use It?
Unless you’re allergic to it, you can use Propylene Glycol every day, even twice a day, without issues or side effects.
What Should You Not Use It With?
Propylene Glycol is one of those ingredients that works well with all other ingredients. You don’t have to worry about incompatibilities with other actives.
What Are The Best Products With Propylene Glycol?
- COSRX Aloe Soothing Sun Cream SPF50 PA+++ (£22.00): A creamy lotion that provides broad spectrum protection without leaving a sticky, greasy feel on the skin. Available at Beauty Bay, Sephora, Stylevana, and Yes Style.
- Dr Dennis Gross Advanced Retinol + Ferulic Texture Renewal Serum ($76.00): A powerful anti-aging serum that targets wrinkles and dark spots on multiple fronts. Exfoliating acids even out the skin tone; retinol and bakuchiol boost collagen; ferulic acid and fellow antioxidants prevent wrinkles; and hyaluronic acid and propylene glycol hydrate skin and plump up fine lines. Available at Cult Beauty, Dermstore, Net-A-Porter, Sephora, and SpaceNK.
- La Roche-Posay Hyalu B5 Hyaluronic Acid Serum ($33.99): A hydrating serum loaded with humectants, including hyaluronic acid, glycerin, and propylene glycol, to deeply hydrate even the driest of skin types. Available at Boots, Dermstore, La Roche Posay, Sephora, and Ulta.
- Paula’s Choice Resist Barrier Repair Moisturiser ($37.00): A low-strength retinol serum for beginners in a moisturising base. Retinol fights wrinkles and brightens the complexion, while the moisturising ingredients counteract its drying effects, keeping your skin soft and supple. Available at Cult Beauty, Dermstore, Paula’s Choice, Sephora, and SpaceNK.
The Bottom Line
Propylene Glycol is safe. It’s a helper ingredient that hydrates skin, allows other ingredients to better penetrate skin, enhances the texture of products, and helps the formula last longer. Unless you’re allergic to it, it won’t irritate your skin. In the tiniest concentrations used in cosmetics, it also won’t give you cancer and won’t cause you any harm.