I know from experience that if you get drug tested, and if you are tested for opiates and are taking vicodin
, it will come up positive.
Likewise if you are taking percocet
. Percs will show + for opiates, as will vicodin, oxycontin, darvocet, roxicet, etc etc... you get my drift.
There is no way they tell whether you're taking percs or vikes- what they CAN do, if they have the time/and or resources is test for the amount of opiates in your system- but they seldom do that.