Facial serums are frequently marketed using claims about “deep penetration”, advanced delivery and powerful active ingredients. Clients may therefore assume that every serum travels through the skin and works deep within the dermis.
The reality is more complicated.
Whether an ingredient enters the skin, where it reaches and what it does when it gets there depend on several factors. These include its molecular size, chemical properties, concentration, stability, formulation and the condition of the skin barrier.
Some ingredients work mainly on or near the surface. Others can enter parts of the epidermis, follicles or deeper structures. A product does not, however, need to reach the deepest layers of the skin to produce a worthwhile cosmetic benefit.
For beauty therapists, understanding this distinction matters. It helps us recommend skincare more accurately, avoid repeating exaggerated marketing claims and explain product choices to clients with greater confidence.
