Welllll, I know that Imuran/azathioprine are synomymous, but isn't 6MP just a slightly different version... designed so that it assimilates in the intestinal tract? Essentially, they're both forms of chemo therapy, and historically chemo has a reputation of being hard on the old hair folicles (sp?). I'd check into the listed side effects of 6MP regarding hair loss. Another likely culprit is malnutrition resulting from poor absorption, ever think of that?