This product is a topical stimulant for eyelash growth. It has been shown to produce longer and fuller (thicker) lashes with ongoing use. Nightly application to the upper eyelid lash line is required to have the effect. Since it causes the lashes to grow for a longer period of time it usually takes minimum of 1 month to start to see the effect. The effect will be continued until you stop using Latisse. Side effects may include redness or irritation of the skin, and when used as a treatment for glaucoma (being placed into the eye itself) a few rare cases of eye colour change (from blue) were noted. This has not been noted when used topically.