Several of the most common ingredients found in lash serums, according to Dr. Monica Li, a board-certified dermatologist and member of the Canadian Dermatology Association, include amino acids (which help to build healthy hair follicles), ceramides (which help to lock in moisture), panthenol (which helps to hydrate and protect lashes from breakage), peptides (which nourish and strengthen the lashes), and biotin (which helps to improve the health of hair by strengthening