I have a MySpace Crohnie friend who got a new tattoo while on Humira... Don't know about 6-MP. I would ask your GI. I was considering getting an IUD for birth control, but they actually suggest against while on immune suppressants. So who knows what affects things. Might be just fine, but a call is easy enough.
Wish I had the guts and commitment to get a tattoo! I stick to henna because I can change my mind! ;-)
--40 year old female, dx as UC in '04 (1st symptoms in '03), switched to Crohn's in '05, 1 fistula, crohn's colitis, limited to large intestine
--rejected (reaction/didn't work): Asacol, AZA, 6-MP, MTX, Remicade, Humira, prednisone
--stuck on methylprednisolone, tried Prochymal in Phase III study (can't wait til it's approved!)
--started Tysabri 3/21/08
--single mom to 10-year-old girl