Once you have started chemo, does your hair fall out right away or later?

Anlagen Effluvium. The onset of anagen effluvium is very rapid. Some individuals who start taking anti-cancer drugs can literally pull their hair out in clumps within the first two weeks. Because these drugs act so quickly and are so potent, the hair follicles have no time to enter into a telogen resting state, as with telogen effluvium, a response to a more moderate environmental challenge.