Can lasix help you flush drugs out of your system?

It is not likely. The World Anti-Doping Agency list that banned Lasix was put out in 2005. Any "new" drug that can beat a drug test is usually only effective until it's special masking ability is neutralized. Four years of labs knowing about something that covers an athlete's steroid use is likely way too long for it to be still useful.

No shield goes for long without someone inventing a way to penetrate it.