How Long for Improvement to Show on Eyebrows Using Latisse?

It is important to note that Latisse works gradually — with full results at week 16. Once you begin, you must continue applying the topical solution each night and follow the directions for best results. If you stop using Latisse at any time, your eyelashes will return to their previous appearance over several weeks to months. Since you are at the 12 week mark, wait to see full results in another 4 weeks. Best of luck. 

For eyelashes, we generally see results between 4-6 weeks. For eyebrows, a little longer. However , if you don't have any viable hair follicles there it won't work. Try a little longer

Latisse is a great product.  Although, it is recommended for eyelashes ( and is FDA approved for this), many patients say that it has thickened their eyebrows as well with nightly use. 

While Latisse is only FDA approved for use on the eyelids, I have many patients who use it on their eyebrows as well(and a few vain guys who use it on their balding hairlines!). As for the eyebrow use, I have seen an effect of longer, fuller and darker eyebrows with Latisse use, however it takes approximately 3 months of daily use to see some effect.

Latisse only works on hair follicles that are alive, meaning they have the potential to grow hair, but just aren't. If what you have is actually hair follicles that are unable to produce hair, Latisse will not make the eyebrows grow there. For eyelashes (which is currently all Latisse is FDA approved for) you will see some results after about 5 weeks with the maximum results at 16 weeks. Since eyebrows are different and longer, you should expect it to take longer to work. However, again, the hair follicles have to have the ability to produce hair!