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1,2-Hexanediol

Well toleratedSolventsolventhumectantpreservative booster

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

Also written as: Hexane-1,2-diol · Hexanediol

What it is

1,2-Hexanediol is a short-chain diol that acts as a solvent and humectant while also lowering the water activity a formula offers to bacteria and fungi. Because its main declared purpose is not preservation, it sits outside the EU's Annex V preservative list, and it is popular in Korean sheet masks where a light, non-tacky feel matters.

What it does well

  • Lets a formula use less conventional preservative while feeling lighter

    It boosts the activity of phenoxyethanol and caprylyl glycol and simultaneously improves slip and hydration, which is why it is common in high-water sheet-mask essences.

    Moderate evidence

Worth knowing

  • Stinging on compromised skin, and rare reported reactions

    The CIR panel reviewed 1,2-hexanediol at reported use levels of 0.00005 to 10% and concluded it is safe in those practices of use and concentration. Tested head-to-head against four other 1,2-alkanediols it showed the lowest objective irritation of the group, although the sensory stinging the same series measured rose as the carbon chain got longer. True allergy is not established for it, but one case of facial contact urticaria traced to a 1,2-hexanediol moisturiser is on record.

    Matters most toPeople with a damaged or very reactive skin barrier.

Where the EU stands

No specific restriction

Not listed in Annex V and not otherwise restricted in EU cosmetics.

Regulation (EC) No 1223/2009 - no annex entry · source ↗

Sources (4)

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

  1. [1]
    Safety assessment of 1,2-glycols as used in cosmetics

    International Journal of Toxicology (Cosmetic Ingredient Review Expert Panel) · 2012 · doi:10.1177/1091581812460409

    The CIR Expert Panel concluded that the 1,2-glycols reviewed, 1,2-hexanediol among them, are safe in the present practices of use and concentration described in the assessment, noting that the glycols are dermally absorbed but that longer chains are predicted to penetrate skin less.

  2. [2]
    Quick Reference Table, September 2017

    Cosmetic Ingredient Review · 2017

    Lists 1,2-hexanediol as safe in the present practices of use and concentration, at a reported use range of 0.00005 to 10%.

  3. [3]
    The influence of alkane chain length on the skin irritation potential of 1,2-alkanediols

    International Journal of Cosmetic Science · 2011 · doi:10.1111/j.1468-2494.2011.00646.x

    Across five 1,2-alkanediols, 1,2-hexanediol showed the lowest objective skin irritation potential, while sensory irritation rose with alkane chain length. The work was done by a cosmetics manufacturer's research institute and published peer-reviewed.

  4. [4]
    Facial contact urticaria caused by a moisturizer containing 1,2-hexanediol

    Dermatitis · 2023 · doi:10.1089/derm.2022.0091

    A single published case of facial contact urticaria attributed to a moisturiser containing 1,2-hexanediol.

Masks that contain 1,2-Hexanediol