"Over-the-counter last serums typically contain peptides that promote healthier lashes, which can lead to enhanced thickness and length," board-certified dermatologist Joshua Zeichner , MD, tells Refinery29. In other words, anything that's not Latisse — the only FDA-approved prescription lash serum for growth — may be able to help strengthen and prevent lashes from falling out, but won't magically transform your lashes into eyebrow-grazing things of wonder.