When you start taking chemo, how long does it take for your hair to fall out and how does it do it?

Anagen effluvium: Hair loss usually begins 7-14 days after a single pulse of chemo. The hair loss is most obvious after 1-2 months. The reason why this occurs is the chemo damages actively dividing hair follicles (anagen) and the hair falls out or becomes thin and easily breaks off. This is more common with combination chemo than with the use of a single drug, and the severity is generally dose related.

Hair loss chemo: Hair loss depends on the exact chemo agent you're given. Not all induce hair loss. There can be retardation of hair loss with chilling of the scalp during the chemo. Please ask the oncologist this question.

1 to 3 weeks: Hair usually falls out 1 to 3 weeks after starting treatment and up to a few weeks afterward. The good news is that it's usually temporary and regrows 3 to 10 months after chemo ends. Hair loss may be all over the body, not just the scalp. It could fall out very quickly in clumps or gradually.