How does phentermine get out of your system?

Mostly kidneys. It is excreted 70-80% in urine unchanged, minimally through the liver.
See below. Phentermine has a half life of 19 to 23 hours.Depending on dose amounts and other factors ..It is excreted in the urine...If you want more information go to asbp web site and search for adipex .Hope this helps.