My experience with this is that it all depends on the policy and attitude of the testing facility, and the employer's requirements. The policy of many facilities that you must have a "current" prescription from a local doctor/pharmacy is sometimes strictly enforced. If you have a script for 30 tablets with instructions for 3 tabs/day, if the date of your test is more than 10 days past the fill date, it is no longer a current script. How strictly this policy is enforced just depends on the people doing the testing. My personal policy is that it is best to get a few days advance notice of the test, stop taking the meds, and say "no" I'm not taking any meds. You only need 3-4 days for hydro to get out of your system enough to pass the test, and drinking lots of water during that time helps. The "local" doc/pharmacy requirement is also an issue for some testing facilities, which is a problem when an OP is involved.

It's certainly true that having to stop taking your meds for several days is a terrible thing to have to deal with. It's such a problem that for me, my employer's drug testing policy was a major factor in deciding which job to get. As far as I'm concerned, it isn't something I'd be willing to do on a regular basis. If I need to take a medication that they test for and they test on a regular basis, they would have to either be willing to accept it or I'd look for a new job.

Sorry for the wordy reply, it's just a subject that has been a major aggravation for me.