Skin Layers, To Scale

Summary

Most over-the-counter actives only reach the stratum corneum and upper epidermis. Dermal targets require formulation work.

Takeaway

Retinoids reach the papillary dermis; vitamin C and niacinamide work mostly in the epidermis.

Citations · 1

1. [01]
   Mukherjee S et al. (2006). Retinoids in the treatment of skin aging. Clinical Interventions in Aging. doi:10.2147/ciia.2006.1.4.327
   Source