Actually, Synthroid HAS been known to cause hair loss, and NOT just from the start of therapy. If you study the literature enclosed with the Brand, I think it might say that. Some people do better on the generic for some reason, and it might be the filler. I do better on the generic version from Mylan Labs., not any other, in combo w/ T3, again from Mylan. That said, people have been known to shed at the start of therapy. It's a journey allright, because response is so individual.