I didn't take a TMPT test, but had frequent blood tests for the first 3 months. I was quite nauseous for the first week or so, but it does pass for the vast majority (a few never get over the sickness); after that, I never had any more issues with feeling nausea on 6MP. Sadly it never actually worked for me, but then nothing did - not even Remicade.
Some people take a low-dose 6MP and allopurinol combination (low dose being one quarter to one third the usual dose, I think). Apparently this reduces liver-related side-effects whilst retaining the full effectiveness of the 6MP. If you do have problems with tolerating 6MP or your TMPT test results are a bit dodgy, that might be worth asking your GI about
Dx Crohn's in summer of 2000. (Yay )
Tried and failed: 5-ASAs, azathioprine, 6MP, Remicade, methotrexate, Humira, various diets.
Had surgery Feb '13 - subtotal colectomy with end ileostomy. First thing to put me into remission in 13 years.
Had second surgery 10th July '15 to reverse the stoma and connect the ileum to the rectum. Officially flaring again. The fun never begins.