Panthenol, also known as provitamin B5, is included in nail care products due to its moisturizing and conditioning properties. There is some scientific evidence supporting its benefits for nails, but the data is limited and not as robust as for skin or hair. Panthenol acts as a humectant, attracting and retaining moisture, which may help reduce nail brittleness and improve flexibility. In vitro studies and some small clinical investigations suggest that topical application of panthenol can improve nail hydration and decrease splitting or peeling. The mechanism involves its conversion to pantothenic acid, a component of coenzyme A, which is essential for cellular metabolism and maintenance of healthy keratin structures, including nails.

However, large-scale, high-quality clinical trials specifically examining the effects of panthenol on nail health are lacking. Most supporting evidence comes from its well-established role in cosmetic dermatology, where it is known to improve barrier function and hydration in skin and hair. Its use in nail products is therefore based on extrapolation of these effects and some preliminary studies. While panthenol is widely used in nail conditioners and treatments, the overall scientific evidence for its efficacy in supporting nail health is modest, justifying a moderate evidence rating.