Why does hyaluronic acid pill?

Naturally present in the epidermis and dermis, hyaluronic acid is essential for skin hydration. Combined with sulfated glycosaminoglycans in the extracellular matrix, it forms a compressible gel that retains water like a sponge, also allowing its circulation and that of dissolved molecules. This property of hyaluronic acid, coupled with its healing and soothing virtues, explains why this active ingredient is frequently used to formulate cosmetic care. However, it should be noted that hyaluronic acid comes in several versions, possessing different molecular weights : low molecular weight (50 - 1000 kDa), intermediate molecular weight (1000 - 1800 kDa), and high molecular weight (> 1800 kDa).

It is often the latter that is affected by the issue of "pilling". This phenomenon, characterized by the formation of small clumps on the skin's surface, can occur immediately after applying a hyaluronic acid treatment or several hours later. While still not fully understood, it's important to note that pilling is completely harmless and does not result from a formulation or product stability issue. Among the hypotheses put forward to explain this inconvenience, we have the large size of hyaluronic acid. By remaining on the skin's surface, this active ingredient forms a non-occlusive film that can interact with other cosmetics applied following the routine. The hyaluronic acid treatment can indeed hinder the skin penetration of subsequent products, leading to pilling.

Not to be confused : Pilling and flaking are different phenomena. Pilling refers to particles of product not absorbed by the skin, while dead skin cells are a result of natural cellular turnover.