When accepting a job a while back I had to take a drug test. I have never used drugs, but I was really curious as to what was tested as I have privacy concerns, etc since I may run for political office someday. I wanted to make sure the samples were destroyed unpon completion of the test and not forwarded to my insurance company for data mining. etc.
The test would look for cocaine, heroin, marijauana, PCP, methamphetimine. Not much more than that. I don't think it looked for LSD. Generally speaking, it will not look for prescription stuff as the company can the be opened to a lawsuit if they deny you employment due to medical conditions etc. I am now on testosterone as part of TRT, so testosterone would be one of those things that if checked and denied employment, I could sue them big time.
I am not sure off all the laws though. If you are applying for the CIA or something, then I am sure there are different laws.