Mercaptopurine
"It seems to "control" the UC symptoms, but it has wreaked havoc with my skin and hair.  I have lost so much hair, and what doesn't fall out, doesn't grow either.  Skin was peppered with little red "spots" that, when they go away, leave brown spots.  I itch.  I am nearly 80, have never been on any medication and I think my body "knows" how foreign this is."