If I Stop Latisse Treatment Will I Lose my Lashes or Will They Just Stop Growing?

Yes, if you stop cold turkey you will lose the gains you have achieved with Latisse.  That's why you should just slow down the application schedule, to every two or three days.  That will be enough follicle stimulation to keep your gains.  And therefore the maintenance dose will be affordable. 

Latisse works by keeping more hair follicles active in their growth phase. This results in MORE and LONGER hairs (in this cases eyelashes). If you stop using Latisse abruptly, a large number of the follicles would go into their dormant stage and the lashes would fall off until the follicles wake up and each re-grows a hair.  It is better to decrease the frequency of Latisse use than to stop its use abruptly.

There are approximately 100 to 150 eyelashes on each upper eyelid. The growth of eyelashes is cyclical, going through 3 stages: a growth phase, a transition phase, and a resting phase. At any given time, numerous hair follicles can be found in each of the different stages. The growth phase of an average eyelash hair is approximately 1 to 2 months. Latisse has been shown to increase the amount of time each eyelash hair remains in the growing phase. The application of Latisse has also been scientifically proven to increase the thickness of eyelash hair as well as the darkness of each hair. This is most likely due to an increased production of pigment within each hair follicle. Typically, within 4 months of application, Latisse can increase the length, thickness, and darkness of eyelashes and improve all the traits that are associated with greater prominence and overall attractiveness of the eyelashes. After three or four months, Latisse can be used much less frequently, usually 2 to 3 times per week. If you stop using Latisse your eyelash hairs will simply return to "normal."