Propylene Glycol
, 2 min reading time
Propylene Glycol
Main Benefit: moisturizer/humectant, solvent, viscosity controlling
Quick Facts
It's a helper ingredient that improves the freeze-thaw stability of products
It's also a solvent, humectant and to some extent a penetration enhancer
It has a bad reputation among natural cosmetics advocates but cosmetic scientists and toxicology experts do not agree
Details
The main role for Propylene Glycol (PG), a colorless liquid, is to improve the so-called freeze-thaw stability of the products. This means that it makes sure that a product doesn’t freeze or melt in low or high temperatures. To achieve this, small amounts - usually less than 2% - are used.
Other functions of PG include being a humectant (helps skin attract water), being a solvent for other ingredients and being a penetration enhancer.
Interesting thoughts
The two most common false accusations found on the internet are that it’s a strong skin irritant and that it modifies the skin to allow toxins to penetrate it.
As for the first one, yes. Propylene Glycol can be a skin irritant if used 100% purity on the skin, but so can many things in their pure form. Think about salt. It’s not the same if you try to eat it in itself or if you put a pinch of it on your food.
Used in small amounts in cosmetics is more than just fine according to every credible scientist and toxicology expert.
As far as modifying the skin, while it is true that Propylene Glycol helps some ingredients to penetrate the skin better, it certainly doesn't modify the skin nor does it allow all the bad stuff to penetrate right into our blood.
English cosmetic chemist, Colin wrote that the skin is very good at keeping things out and getting some good ingredients into it is actually not easy. According to his experience Propylene Glycol is not a very good penetration enhancer and fairly large (10-25%) amount is needed for this function. But more than 10% can be irritating, so it’s very rare that a cosmetic product contains this large amount.
Scientists at the Beauty Brains are even more accepting of Propylene Glycol as they claim that it is safe for ingestion (it can be a food additive!) AND safe for use in injected drugs, so it’s unlikely to cause any problems in a topical cosmetic product applied on intact skin.
Propylene Glycol is a helper ingredient and is not especially good for your skin. But used in small (<5%) amounts it’s absolutely fine, not poisonous and there is no reason to be afraid of it.
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