Ingredient guide

Propylene Glycol: The Workhorse Humectant, and When It Bothers Skin

Propylene glycol helps products hold moisture and carry actives. Here's what it does, the difference between irritation and allergy, and who should watch it.

What it is

Propylene glycol (PG) is a humectant and solvent: it helps products hold water, keeps them from drying out, and helps dissolve and carry other ingredients into the skin. It is one of the most common ingredients in skincare.

Irritation vs allergy

For most people PG is well tolerated. Two things can happen in sensitive individuals: mild irritation (stinging on compromised skin, especially at higher concentrations), and, less commonly, a true contact allergy. PG is a recognised, if relatively infrequent, allergen, and it is included in some dermatology patch-test panels.

Who should watch it

People with eczema or very reactive skin who sting or flare with many products may find PG is one contributor, particularly in leave-on products where it sits on the skin. For most people it is not a concern.

Where it hides

Moisturisers, serums, makeup, deodorants and some medicated creams. Look for Propylene glycol, PG, 1,2-Propanediol or Propane-1,2-diol.

Check products against your list

To check a product, INCIBeauty lets you look up a product and read plain-language notes on each ingredient, with a community that rates them, and a free analyser like Skincarisma lets you paste a product at your desk and see propylene glycol flagged in the ingredient list. These rate a product on general criteria rather than against your own list.

Once you know what you are screening for, a personal-list app like ClearaScan lets you save propylene glycol once and scan any product to flag only your triggers. It also keeps a Reaction Journal for flare-ups, a shared Care Circle so family or carers can scan for you, and a Trusted Products list for items you have cleared, and it is currently in early access. (Disclosure: our editor co-founded ClearaScan, and we are not paid to mention the others.)

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A note on this content. The Sensitive Skin Lab publishes general educational information, not medical advice. If you suspect you have an allergy or sensitivity, consult a qualified dermatologist or allergist. Product formulations and labels change without notice, so always check the ingredients on the product itself.