Hair thinning/loss is a possible side effect of all AI's. I started Anastrozole after chemo in October of 2020 (total hair loss). It seemed my hair grew back slower, but since this was a first time experience I wasn't sure if this was normal. I switched to Letrozole 17 months ago and my hair is growing at its normal rate. It's thinner than I'd like, but could also be the normal aging process (I'm 68). Everything came back thinner/sparser - eyelashes/brows, all body hair. I don't miss the body hair, but I do miss the eyelashes - there but not enough to bother with mascara. I do use Nioxin shampoo and conditioner and make sure to massage it into my scalp for several minutes.