A test can report the presence of a specific illicit or prescription drug and the person has not used these drugs. And then it is up to you to prove your Innocence and you are guilty until you do prove it. It is important that if you facing drug testing, that you give the drug testers a complete and accurate history of all prescription, over the counter drugs as well as any vitamins, dietary supplement or herbal drug use prior to the time of the sample collection. The more the drug testers know about these kinds of things before hand the better. It might also be a good idea to take any prescriptions with you that have been provided by a doctor.