Panthenol is a precursor of pantothenic acid (vitamin B5), hence "pro-vitamin B5". Known in skincare for its soothing and moisture-supporting properties, it appears on INCI lists simply as "Panthenol".
It is frequently chosen for sensitivity-prone skin. Its gentle profile is the main reason it appears in care routines for skin that feels irritated, in post-shave products and commonly in scalp products.
Panthenol is water-soluble and does not replace barrier lipids on its own. It works best when soothing ingredients like it are presented alongside skin-identical lipids and humectants in a balanced formulation.