Propylene Glycol in Skincare: Safety and Who Should Avoid It
Propylene glycol is a colourless liquid that holds water in skincare and helps other ingredients dissolve and spread. The Cosmetic Ingredient Review has found it acceptable at normal cosmetic levels, and a small share of people react to it.
TL;DR
- What it is: a small, water-loving molecule used as a humectant and solvent.
- What it does: pulls water towards the skin and keeps formulas smooth and easy to spread.
- Is it safe: the CIR found it safe for cosmetic use at concentrations up to 50%.
- The catch: it can irritate or, less often, cause an allergic reaction, mostly on damaged or reactive skin.
- Not the same as antifreeze: that is ethylene glycol, a different chemical.
- Our position: it is not in any of our formulas.
What is propylene glycol?
Propylene glycol is a clear, almost odourless liquid that mixes with water and oil. Chemists call it a glycol, and on a label you will see it as propylene glycol.
It turns up in moisturisers, gels, toners, deodorants, shaving creams and many prescription creams. It also appears in some foods and household products, which is where a lot of the confusion starts.
What does propylene glycol do in skincare?
It does three jobs. It is a humectant, so it draws water towards the skin.
It is a solvent, so it dissolves ingredients that would otherwise clump or separate. It also helps a formula feel smooth instead of tacky.
Because it carries other ingredients well, it is sometimes described as a penetration enhancer. That is part of why people with reactive skin are often told to be careful with it.
Is propylene glycol the same as antifreeze?
No. Antifreeze is usually ethylene glycol, which is toxic if swallowed. Propylene glycol is a different molecule with a different safety profile.
The two get mixed up because they share a chemical family and a name. A skincare label that lists propylene glycol is not listing antifreeze.
Is propylene glycol safe on skin?
For most people, yes, at the levels used in cosmetics. The Cosmetic Ingredient Review concluded in 1994 that propylene glycol is safe for cosmetic use at concentrations up to 50%.
That conclusion came with a caveat about the person using it. The same review noted irritation and sensitisation at concentrations as low as 10% under occlusion in people with normal skin, and 2% in people with dermatitis.
Can you be allergic to propylene glycol?
Yes, but it is not common. DermNet NZ reports allergy in up to 3.5% of people tested for suspected contact dermatitis, and more often in people with atopic or compromised skin.
Propylene glycol is both a weak irritant and a weak sensitiser. That makes a true allergy hard to tell apart from simple irritation without a patch test from a clinician.
Who should be careful with propylene glycol?
If your skin stings, flushes or flares with gel moisturisers, serums or medicated creams, propylene glycol is worth checking for on the label. Skin with a damaged barrier is more likely to react to almost anything, including this.
Our guide to patch testing skincare properly is a good first step. If you keep reacting and cannot work out why, see your GP or a dermatologist.
How do you use products that contain propylene glycol?
Patch test a new product on a small area first. Introduce one new product at a time so you can spot the culprit if something goes wrong.
If a product stings or leaves skin red, stop using it. Reactive skin does not need to push through.
What other ingredients do the same job?
Several humectants cover similar ground. Glycerine is the best known, and sodium PCA is another gentle option.
Different formulas lean on different humectants. There is no single right choice, only the one that suits your skin.
Safety and typical concentration range
The CIR safety conclusion covers propylene glycol and polypropylene glycols in cosmetics at up to 50%. Real products usually sit well below that, and the amount depends on the formula.
Use level matters because the reactions the CIR described were concentration dependent. A leave-on gel with a small amount is a very different thing from an occluded patch at high strength.
Do we use propylene glycol at Dope Skin Co?
No. Propylene glycol is not in any of our current formulas. Our formulas use other humectants instead, including vegetable glycerine, and we make them in small batches in Sydney.
If you are not sure what suits your skin, the skincare quiz points you to a routine in a few minutes.
FAQ
Is propylene glycol bad for sensitive skin?
It does not suit everyone. Most people tolerate it, but people with reactive or damaged skin are more likely to sting or flare.
Is propylene glycol plant-derived or synthetic?
It is usually made industrially from propylene oxide. Some producers make it from plant glycerol.
Does propylene glycol clog pores?
It is a water-loving liquid, not an oil, so it is not generally described as pore clogging. Whole formulas behave differently from single ingredients.
Is propylene glycol the same as polyethylene glycol?
No. Polyethylene glycols, or PEGs, are a separate group of ingredients with different uses.
