How long does it take simvastatin to leave your system when u stop taking it?

24-48 hours. The listed half life is 4 hours. That means after 4 hours 50%is gone. After 6 half lives (24 hours) over 96% is gone from your system. However, side effects from simva may take more time to resolve. Eg. 2-4 weeks for muscle aches. Hope this helps.