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Pentylene Glycol

Well toleratedHumectanthumectantsolventantimicrobial

No meaningful concern for most people; irritation is possible but rare.

Also written as: 1,2-Pentanediol

What it is

Pentylene glycol is a five-carbon alcohol that hydrates skin while also inhibiting bacterial and fungal growth. Because of that dual role it appears in many formulas marketed as preservative-free: it does preservative work without being classified as a preservative under EU rules.

What it does well

  • Hydrates and reduces the need for conventional preservatives

    Its antimicrobial activity lets formulators cut back on ingredients like phenoxyethanol, which is useful for people trying to avoid those specifically.

    Moderate evidence

Worth knowing

  • Can sting or irritate at higher concentrations

    The same property that makes it antimicrobial means it is slightly more irritating than butylene glycol at the levels needed for preservation. The Cosmetic Ingredient Review's conclusions table records a reported use range of 0.001 to 5%, and on the packs here it sits high enough to match that preservative role: of the forty masks whose list reaches the point where ingredient order stops indicating quantity, twenty-five print pentylene glycol above that point. Most people notice nothing.

    Matters most toPeople with sensitive or reactive skin who notice tingling from leave-on products.

Where the EU stands

No specific restriction

Permitted in EU cosmetics with no concentration limit. It is not listed in Annex V (approved preservatives) because it is used for other functions, and it carries no restriction.

Sources (1)

Every link goes to the original: a journal, a PubMed record or an EU document.

  1. [1]
    Quick Reference Table: ingredients found safe in the present practices of use and concentration

    Cosmetic Ingredient Review · 2017

    The Cosmetic Ingredient Review's conclusions table lists Pentylene Glycol with an S conclusion - safe in the present practices of use and concentration - over a reported use range of 0.001 to 5%, citing IJT 31(S2):147-168, 2012. That 2012 assessment is where the ingredient was reviewed; the Panel's later Alkane Diols final report of 13 June 2018 lists Pentylene Glycol (1,2-pentanediol) in its table of ingredients previously reviewed as safe as used (2012), and does not restate a concentration for it. Checked 31 August 2026.

Masks that contain Pentylene Glycol