I've been on Asacol, then Colazal, for the past 15 years. I started losing my super thick hair over 10 years ago. I'd say I lost 3/4 of my hair at that time. My hair is now very thin, but still very long. So it never grows back to the thick hair you once had I'm sorry to say, but it hasn't all fallen out. Also the hair loss stops at some point and your hair just stays thin. For me, the hairloss picks back up whenever I have signifcant stress in my life.
I've been tapering off Prednisone (which I've been on for over a year now) and that has really made the hairloss pick up. It's as bad as it was when it first started falling out except this time I don't have much hair to lose! I'm hoping it stops soon and I won't be going on Prednisone again that's for sure!