Active Ingredients: Glycol

Reyanna Ng Beauty Expert
Active Ingredients: Glycol

What is Glycol? Is it actually bad for your skin?

We are somehow put off by scientific names in our skincare product’s ingredient list and commonly on the “avoid” list of skincare ingredients are propylene glycol and butylene glycol. A quick search on the internet will bring up major red flags stating that propylene glycol and butylene glycol are toxic and carcinogenic. But if that isn’t true? why is it still used in plenty of skincare products, or are the statements wrong? We’re here to break that assumption and tell you whether or not you should be avoiding those 2 ingredients and why they are still being used in plenty of skincare products.

Firstly, to start off, what are glycols? And what are the differences between propylene glycol and butylene glycol?

Glycols are ingredients that contain 2 OH (alcohol) groups. Propylene glycol contains 3 carbon atoms while butylene glycol is slightly larger and contains 4 carbon atoms. Both propylene glycol and butylene glycol function the same way. They are humectants, solvents, emollients and preservatives, and can be found in a wide array of products and formulas, not only in skincare. It is colourless, odour-less and completely water-soluble. Both are organic alcohols derived from petroleum.

 Propylene glycol is the most common moisture-carrying ingredient besides water itself which is why it is so prevalent in skincare products. It is slightly smaller than butylene glycol and is considered to be more irritating to the skin. The EWG rates propylene glycol a 3 out of 10 (10 being the most hazardous). Propylene glycol can sometimes be referred to as “propanediol”, and something interesting to know about is that most brands have switched to using propanediol in their ingredient list since propylene glycol has been on the watchlist. 

Butylene glycol is a slightly larger chemical compound and is found to be less irritating which is why it is now being used more as an alternative to propylene glycol. The EWG rates butylene glycol a 1 out of 10 (10 being the most hazardous).



Attracts water

  • Both propylene glycol and butylene glycol are good humectants that attract water from the air and hold onto that water to keep the skin hydrated. When used in topical applications, it helps give our skin that hydrated, dewy glow.

Moisturises the skin

  • Being humectants, they both offer moisturising qualities and smoothens the skin without a sticky residue.

Smoothes the skin

  • In addition to being humectants, both can also work as an emollient by creating a barrier on the skin that prevents water loss and softens the skin.

Plumps the skin

  • As we age, our skin tends to become depleted of a component called Natural Moisturising Factor (NMF). When this happens our skin becomes more dehydrated and this emphasises wrinkles, fine lines and contributes to flaking skin and roughness. With propylene glycol helping to hydrate the skin, it counters water loss that accompanies ageing skin. With your skin being moisturised, it will appear more supple and fuller.

Helps other ingredients

  • Propylene glycol and butylene glycol are commonly used as solvents as they are good at dissolving ingredients that aren't very water-soluble, meaning that they help active ingredients penetrate and spread better into the skin, making them more effective.

Antimicrobial effects

  • Both ingredients have slight antimicrobial effects.
  • Its non-oily after-feeling and antimicrobial properties make it ideal for those with acne-prone skin.


Final Thoughts?

So why are we told to avoid both these ingredients? The main reason is behind the idea that it is petroleum-derived, and things derived from petroleum are harmful to the skin. There are plenty of safe chemicals that are derived from petroleum too, for example, plastic. Where something comes from doesn’t tell you much of its toxicity, the most important part is the formulation. Both propylene glycol and butylene glycol are safe when used in products that are formulated to be non-irritating. The other reason behind why we are told to avoid these 2 ingredients is the fact that it is a penetrating-enhancing ingredient. Although it does help active ingredients penetrate the skin better, improving its efficacy, many state that this benefit could also pose threats as it may allow harmful toxins in the air to better permeate the skin which can cause further damage. However, this reasoning is a double-edged sword and it depends on how you see it, because at the end of the day you can guarantee that both ingredients will improve the effectiveness of your other skincare products.

So at the end of the day, it doesn’t look like you should be worried about propylene glycol or butylene glycol in your skincare products as they’re relatively safe (all depending on the formulation) and harmless to the skin.


What to note?

  • As we mentioned, there are multiple ingredients that have the word glycol in them and ethylene glycol is one that you should avoid. Do not confuse propylene glycol or butylene glycol with ethylene glycol as the latter is an ingredient used in antifreeze (an engine coolant) and is considered toxic and harmful.
  • Although propylene glycol and butylene glycol is safe to use, those with chronic skin conditions like eczema and dermatitis may find themselves more prone to an allergic reaction. So we recommend conducting a patch test prior, as with all new products.


Products we recommend 

Paula’s Choice 10% Azelaic Acid Booster

paulas choice azelaic acid booster

This multi-action, all-skin-types booster targets several stubborn skin concerns at once thanks to its powerhouse blend of azelaic and salicylic acid, plus plant-derived brightening and soothing ingredients. Butylene glycol is another key ingredient that not only promises hydrating benefits but helps the other active ingredients to better penetrate the skin. 


Paula's Choice Invisible Finish Moisture Gel

paulas choice invisible finish moisture gel

Delivers visibly smoother, softer, and younger-looking skin with a weightless skin-refreshing feel. It’s the ideal ultra-light moisturiser for oily skin that needs hydration and protection from environmental assault. It is a stunningly advanced formula with a brilliant array of antioxidants and skin-restoring ingredients. The added butylene glycol helps to hydrate the skin without leaving an oily-residue and enhance other active ingredients. 


Paula's Choice Clear Oil-Free Moisturiser 

paulas choice clear oil free moisturiser

The frustration of finding the best moisturiser for acne-prone skin is over. This non-greasy moisturiser provides water-light hydration, eliminates dry, flaky patches, and visibly corrects issues unique to acne-prone skin—without adding oil, clogging pores or making breakouts worse. It contains pumpkin and blueberry extracts to calm redness, ceramides to strengthen the skin, niacinamide that improves skin tone, and propanediol (another name for propylene glycol) to help hydrate the skin. 


COSRX Advanced Snail 96 Mucin Power Essence

coxrx advanced snail 96 mucin power essence

COSRX Advanced Snail 96 Mucin Power Essence is made with all-natural domestic 96% snail secretion filtrate that hat transform the skin while keeping in the moisture and encouraging the real power of skin in a healthy way.  It replenishes nutrients to the skin to prevent and repair damages and fills the skin with elasticity for a healthier, younger looking skin. Panthenol and sodium hyaluronate are humectants which literally helps your skin attract moisture to your skin like a magnet. It also includes butylene glycol that adds to the hydrating benefits but also enhances the efficacy of other ingredients.


Cetaphil Gentle Facial Cleanser

cetaphil gentle skin cleanser

This cleanser gently cleans and moisturises without stripping skin’s natural oils. It is formulated o work for all skin types, even for babies and very sensitive skin. It’s the dermatologist-trusted cleanser for healthy and beautiful skin. It contains propylene glycol to help hydrate and moisturise the skin while washing away all the impurities in the skin.

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