i tried revivogen for six months and did not notice much regrowth, it did however slow down my hair loss, less hair in the shower, on my pillow, etc..., but since it did not do what i thought and wanted it to do, regrow hair, i stopped with the treatment. about two weeks after i stopped using the shampoo and serum, i noticed more hair loss, it seemed that without revivogen, my hair is weaker. they do say on the site that it does not regrow hair, but does make the existing hairs stay on stronger. i might never go back to revivogen again because it's pretty pricey, i'm currently on nioxin, with pretty much the same results. so i think both products are pretty good. i bought nioxin because this one guy who cuts my friends hair reccommended it to me. it doesn't really regrow hair, just makes your existing hair more healthy.