Many cancer survivors report problems with eyelashes and eyebrows continuing to fall out, or growing in thinner or shorter, several years after they completed chemotherapy. Chemotherapy can cause long-term changes to the hair follicles, which is why the hair on your head often comes back a different color or texture than it was before. The same thing is happening with eyelashes and eyebrows. Still, it's worthwhile to talk to your doctor and ask if this is normal, and if there is anything you can do. There are other conditions, such as thyroid problems, that cause thinning of the eyelashes and eyebrows, and your doctor can help you rule those out.