[Focault's Pendulum]

There could be several reasons why you were passed previously, including test sensitivity to the substance, or a metabolic situation in your body that produced more concentrated levels on the test that day.

I have passed over 50 drug tests since 2001. Always on this medication. This was not a metabolic reaction. this was a screw up by a lab tech who didn't know the difference between a beta blocker and a narcotic.

I had to fight it and get another independent lab to refute the results. That was six months out of my life.

[ican'tbelieveit]

That isn’t how the tests are performed. Periodically a test will generate a positive where it hasn’t in the past for a lot of different reasons. False positives are inherent to the system, just as false negatives are.

There should probably be a better system to dispute positive samples. I can see how that would make you bitter at the process.