Are you sure... I send people for chain of custody drug screens and was told make sure if they take OTC like ephedrine they stop a few days before or tell the evaluator they take it.
Yes I'm sure. Unlike most people, I don't waste my time and everyone else's by posting shit I am not sure of.
There are literally hundreds of substances which can cause false positives on immunoassay. How ridiculous is it to believe that there is no confirmation of positives?
If a sample has to be sent for GC/MS, it costs more money. So, the only reason they tell you to instruct people on OTC medication intake is to save money on GC/MS testing. That, or they don't know their business very well. But I would suspect that any company who performs a significant amount of drug screens would instruct their people based on cost management measures. The alternative is not to send an aliquot for GC/MS, deny employment to a person who has never used drugs and get sued.
Now, some mom and pop operation may have the idea that they want to perform drug testing but don't want to incur the cost of using a real lab. So they use spot immunoassay and just ask the person what they took if they get a positive. But any real company with competent legal advice or any government agency is going to use a real lab.
Not to mention, I spent 8 years of my life in intensive drug screening for the state medical board as well as felony probation. I was never off of ephedrine during that time and I never failed a drug test. So besides understanding drug screening protocols, I have tested this personally at least a few hundred times and never managed to get a false positive. I would have had to back up five years at "hard labor" if I had a positive. Or possibly kiss my livelihood and all those years I spent in school goodbye for good. So if I'm willing to bet 5 years in prison and my livelihood on it, I am quite obviously sure.
Rex.