If you are a chronic user of ativan then it will stay in the system for up to 2-3 weeks. If you rarely take ativan then it will take about 3-7days to get 4 mg out of the urine. There are other factors that come into play though like, weight, metabolism, water intake, exercise, and other medications you have been taking at the time. To be safe I would wait a week for 4 mg to flush through the system. But if you want to speed the process up drink a lot of water and make sure to exercise enough to break a sweat. My old trick was hitting up the Y-mca steam-room after a nice jog and work out. Hope this helps. Peace