Currently, bimatoprost, which can be found in the prescription-only Latisse, is the only FDA-approved ingredient that’s been proven to promote longer, thicker, darker lashes. Over-the-counter eyelash serums — like the ones featured in this article — instead work to nourish and condition your lash hairs. While this doesn't stimulate new lash growth, improving the strength and hydration of your lashes can boost the appearance of fuller lashes by helping to prevent breakage and lash loss. lash..serum..growth I was lucky that I didn’t experience any redness or irritation, as I read about in some of the Google reviews. As far as results go, I noticed results after about four weeks–mostly toplash organic brow gel that my lashes were both longer and fuller. I’d say within six weeks or so, other people started noticing, too. I couldn’t believe that I was the person that was getting DMs asking me about what mascara I use.