Here’s the thing: Eyelash serums are not always formulated to actually make your lashes grow faster but instead nourish the lashes you already have. While some people may experience growth when using nourishing products, there isn’t much clinical evidence to back up those claims.
This doesn’t mean OTC eyelash serums are useless, however. “I do think that the emollient properties of these oils may be helpful if the eyelashes or brows are becoming brittle and broken due to the use of mascara, adhesives, false eyelashes, and curling devices,” board-certified dermatologist Hadley King, M.D., tells mbg.
Some more popular ingredients, like peptides, have been researched in recent years and provide promising results for eyelash health. In this study, researchers found that some peptides (myristoyl pentapeptide-17 and myristoyl hexapeptide-16) stimulate keratin production, a key factor in hair growth. The results of their study included increased lash curl, length, volume, and thickness. Increased growth itself, however, was not documented.
To sum it up: OTC lash serums can certainly encourage healthier lashes (read: longer, stronger, thicker, etc.) but will not likely encourage increased growth, per se. When your lashes are healthier, though, fallout and brittleness will likely decrease, meaning you’ll hold on to your lashes for longer. And strong, thriving lashes certainly look longer, too.