This is interesting...I take a boatload of medications for a medical condition. I am subject to randon drug testing as well, and believe me, you don't know when you are going to get tapped on the shoulder to report for it. (and I am ok with it, I pass it every time)
I had a couple friends at work, who went on a med that starts with the letter 'x', and they talked about it openly, then having an off day, management sends them home telling them it is impairing their ability to do their job.
I have also seen it where a person works, taking the same med "x" and has an off day, but since management doesn't know they are on that med, doesn't think twice about it.
I once asked if the drug, "x" was one that anybody taking would be sent home and the answer I got was "NO", it's not necessarily the "x", but rather it is perceived that it is causing an effect on the employee. And I believe that is fair.
I have taken a med that for most people will make them so drowsy, but I have taken 2 at a time, 4 times a day and I don't get sleepy....so in that instance, I can handle the med whereas someone else cannot (and this time I an not talking about drug "x".
I went for a random test and started to get chatty with the lady that had to watch and follow the chain of custody......she immediately told me to shut up, that she did not need nor want to know about anything. She simply said, 'it will be tested, if anything is detected, the doctor would request proof of the rx, but nothing would be reported to HR if it is prescribed and have valid proof."