I just started working as a pharmacy tech and occasionally take dextroamphetamine for work/going out and will get randomly drug tested via saliva test. I had to do one before getting hired and knew about a couple days before so I knew to stay clean.

I just got a Concerta ER script and want to know if I happen to get randomly drug tested again and know I will test positive for amphetamines from the dextroamphetamine can I reasonably blame it on my Concerta script?

This pharmacy I work at doesn't dispense my medicine btw if that matters. I will be trying to switch as fast as possible to an amphetamine but I just wanted to hear anyone's thoughts, thx! And if anyone knows from experience how long your job took to randomly drug test you after being hired lmk but I'm sure it's probably different if I'm working in the back of a pharmacy.