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Sclerotium Gum

Well toleratedThickenerthickeneremulsion stabiliserskin conditioning

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

Also written as: Scleroglucan · Sclerotium rolfsii gum

What it is

Sclerotium gum is the polysaccharide produced by the fungus Sclerotium rolfsii - some grades come from Sclerotium glucanicum instead - and grown by fermentation rather than extracted from a plant. Structurally it is a beta-glucan: a backbone of beta-D-(1-3)-glucopyranosyl units with a beta-D-glucopyranosyl unit linked (1-6) to every third one. It is non-ionic and disperses easily in cold water, which is why it survives formulas with salts or acids that would thin a carbomer.

How it shows up on a label

Reported use runs from 0.003 to 2%, so its place in a list says less about quantity than usual: on five of the eight masks here whose list shows the point where ingredient order stops indicating quantity it sits below that point, and on three it sits above it while still being a small number.

What it does well

  • Thickens and stabilises across a wide range of formulas

    Its recorded cosmetic functions are emulsion stabiliser, viscosity-increasing agent in aqueous systems and skin-conditioning agent. Being non-ionic, it tolerates electrolytes and a broad pH range better than charged thickeners do. None of that is a claim about skin.

    Strong evidence

Worth knowing

  • Structural, with no effect of its own on skin

    Like the other microbial gums, what it contributes to a mask is body and stability. Whatever the mask does for you comes from the water it holds against the skin and from the rest of the list, not from the gum. Its listing as a skin-conditioning agent reflects feel rather than a biological action.

Where the EU stands

No specific restriction

Not restricted under the EU Cosmetics Regulation; it appears in no annex and has no concentration limit.

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

Sources (2)

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

  1. [1]
    Safety Assessment of Microbial Polysaccharide Gums as Used in Cosmetics

    Cosmetic Ingredient Review, International Journal of Toxicology 35:5S-49S · 2016 · doi:10.1177/1091581816651606

    Sclerotium Gum is named in the Expert Panel's safe list: the panel "concluded the microbial polysaccharide gums listed below are safe in the present practices of use and concentration in cosmetics", across 34 gums. The supporting report defines Sclerotium Gum (CAS 39464-87-4) as "the polysaccharide gum produced by the fungus, Sclerotium rolfsii" consisting of "the basic backbone of beta-D-(1-3)-glucopyranosyl units with a beta-D-glucopyranosyl unit (1-6) linked to every third unit", gives its reported functions as "emulsion stabilizer; skin conditioning agent-misc.; viscosity increasing agent-aq.", records it in 193 cosmetic formulations over a use range of 0.003 to 2%, and describes it as non-ionic and readily dispersed in cold water. Checked 26 September 2026.

  2. [2]
    Quick Reference Table: CIR conclusions by ingredient

    Cosmetic Ingredient Review · 2024

    The quick reference table lists Sclerotium Gum with an S conclusion - safe as used - citing International Journal of Toxicology 35(Suppl. 1):5-49, 2016. Checked 26 September 2026.

Masks that contain Sclerotium Gum