Prescription Latisse is one of the few products that actually lives up to the hype. In a matter of months, lashes grow fuller longer and darker. They grow so long that they can even irritate the cornea. So to avoid this Latisse is often only applied to the outer half of the upper lid. I once tried it on my lower lid and started becoming a hairy monster around my eyes. There are side effects that can occur which include darkening of the eyelid, redness, itchiness and very rarely changes in the color of the iris. I personally also use Latisse on bald spots in my eyebrows and love it!
A couple of over-the-counter products also work well. The active ingredient in rapid-lash or revita-lash are similar to the one in Latisse. I have used it in the past and have been very happy with the results and it is a less expensive alternative.