The first lash stimulators to hit the market a few years ago contained an active ingredients called prostaglandin, which, although originally used in glaucoma medication, had the unexpected side effect of enhancing eyelash growth. But concerns over safety-the FDA doesn't regulate the use or concentration of active ingredients in over-the-counter products-along with a patent infringement lawsuit by Allergan (who uses the ingredient in their prescription glaucoma medication and their new prescription lash stimulator, Latisse) led to the reformulation and introduction of new products containing blends of peptides and herbal extracts that work by stimulating the hair follicles, leading to lash growth.
Some doctors are confident that these non-prescription options can, indeed, achieve growth and thickness. For maximum results, these products should be applied to the lash line nightly like liquid liner. If you stop using the product, lash growth returns to its previous rate, and longer, darker lashes eventually fall out.