Any decent pain doc is aware of what can cause a false pos. Several years ago, my pain doc of ten years, came in the exam room, chuckled and said I tested positive for something I don't even take. He told me not to panic, that he trusted me implicately, and he would get to the bottom of it. We discussed my diet, any OTCs I might have taken and whether my primary doc had put me on something new recently. He had. Neither my pain doc nor the primary knew it would do this. Pain Man did some digging and called me to let me know that it was rare but has happened before. End of story.