I've been on azathioprine for 6 days already and yesterday was the first day of complete normal temperature and not needing Tylenol. It's been 3 days not needing Tylenol to be able to get up in the morning. No one ever believes me but I metabolize azathioprine really fast and I thought at first I'm imagining it but not needing Tylenol when I needed 3-4 a day before is quite telling.