Hyaluronic Acid

HA can bind up to 1,000 times its own weight in water, making it an exceptional surface hydrator and skin protectant. High-molecular-weight HA forms a protective barrier on the skin surface and can act as an osmotic pump to help water-soluble actives penetrate deeper. Low-molecular-weight HA (≥50 kDa) may hydrate slightly deeper into the epidermis, support skin self-defense, and has shown benefit in inflammation-related conditions such as rosacea and seborrheic dermatitis.

Ultra-low molecular weight HA (<50 kDa, particularly ~20 kDa) has shown potential pro-inflammatory activity in reconstituted human epidermis models; cautious users may wish to avoid ultra-low MW versions. The INCI name alone does not reveal molecular weight, so the specific form in a product cannot be determined from the ingredient list.