Yep. When I first started treatment for Crohn's almost 2 years ago, I noticed a gradual increase in hair thinning and bald/open patches on my head.
I am in my first full remission right now and my doc lowered my dose of 6mp and Asacol about two months ago when I discussed the hair loss along with other symptoms. Since then my hair doesn't look as thin as it was with my ever-increasing dosages of medications.
I've been using Organix Biotin Shampoo & Conditioner and it really does a decent job of keeping things looking a bit fuller. Supplements are another route to go if you have severe thinning, just make sure you talk to your doctor first as an overdose of biotin can interact with other vitamin storage, blood sugar and cause skin conditions in your body.