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Propylene Glycol

Propylene GlycolHydrator

Small-molecule humectant and solvent. Effective at pulling water into the skin; can sting compromised barriers.

What it does

Propylene glycol is a workhorse humectant and solvent. It pulls water into the upper skin layers and dissolves a wide range of cosmetic actives, which is why it's frequently the second or third ingredient on serum and treatment INCIs. The internet's 'antifreeze' association is misleading — pharmaceutical-grade propylene glycol has been used safely in topical and oral products for decades. The honest tradeoff: at higher percentages on already-irritated skin, it can sting.

The evidence, graded

expert consensusIf skin is reactive, peeling, stinging, or burning unexpectedly, pause all actives and rebuild the barrier with simple cleanser, ceramide-rich moisturizer, and SPF for 2–4 weeks before re-introducing actives one at a time.Lodén 2003 · American Journal of Clinical Dermatology ↗

Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.

Also known as

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Pairs worth knowing

Glycerin · works together ↗Hyaluronic Acid · works together ↗Panthenol (Pro-vitamin B5) · works together ↗

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