What is it?
A form of hyaluronic acid in which the long chains of sodium hyaluronate are chemically linked to one another with divinyl sulfone, turning separate strands into a three-dimensional network. It is used in moisturizers, serums and other leave-on skin care as a humectant, meaning it attracts and holds water, and as a skin-conditioning agent. US product listings in 2025 included it in more than 5,000 formulations.
Key information
- It has the same backbone as sodium hyaluronate, but its chains are chemically crosslinked with divinyl sulfone.
- The CIR began reviewing it in 2026 and found no published toxicity, irritation or allergy studies on the crosslinked ingredient itself.
- A 2025 industry survey reported use at up to 0.47 percent in leave-on face and moisturizing products.
- The EU places no restrictions on it.
More information
Hyaluronic acid is a long sugar chain that occurs naturally in the body, and sodium hyaluronate is its sodium salt (see our Sodium Hyaluronate profile). To make the crosspolymer, the chains are reacted with divinyl sulfone, a small, highly reactive chemical that bridges one chain to another. Crosslinked hyaluronic acid is also used in injectable dermal fillers, although the filler research the CIR cites involves a different crosslinker.
The Cosmetic Ingredient Review (CIR) Expert Panel has found hyaluronic acid and sodium hyaluronate safe as used (2009, confirmed in 2023). In March 2026 it began a separate review of the crosslinked forms. Its literature review found the ingredient in 5,396 US formulations in 2025, at up to 0.47 percent in leave-on face and moisturizing products, but no published studies of skin absorption, toxicity, genetic damage, skin irritation, allergy or eye irritation for this ingredient, and no unpublished data had been submitted. The only impurity specification it found was a heavy-metal limit of 10 ppm.
Divinyl sulfone itself is hazardous: in notifications to the EU chemicals agency, companies classify it as fatal if swallowed or in contact with skin. Once reacted into the network it is no longer free divinyl sulfone, but we found no published measurements of leftover crosslinker in the cosmetic ingredient.
Reality check: there is no evidence that sodium hyaluronate crosspolymer causes harm, and it is widely used. But it is not simply “hyaluronic acid,” and its own safety has not yet been assessed. The CIR review now under way should help fill that gap.
Sources: Cosmetic Ingredient Review: Safety assessment of sodium hyaluronate crosspolymers as used in cosmetics, scientific literature review (March 2026); PubChem: Divinyl sulfone (GHS classification); European Commission CosIng: Sodium Hyaluronate Crosspolymer
