I am a chronic pain patient...been going to an anesthesiologist certified in pain management for a little over three years now. I have fibromyalgia, cervical syndrome and many issues with chronic skull pain(not migraines or headaches) due to having surgery in my brain stem. I have been on pretty much every narcotic(legal/prescribed) before finally settling on a regimen of narcotics and a benzo(for muscle relaxation) that works(and the dosages are pretty high) When I first started in pain management I took a leave of absence for about 6-8 months because I was very naive to opiates and they honestly did make me downright dopey(and of course I would NOT work around patients in that state). Taking the leave was my choice, my supervisor said I could sit and push papers but even doing that would make me fall asleep(I just needed the time off to get better after a car crash and to get used to the medications). Anyway in my honest opinion hiring a person based on their use of prescription narcotics(including states that legalize marijuana should be taken on a case by case basis if the company has a policy on drugs in the work place). If a person shows up and says they are on such and such opiate for chronic pain and they slur their speech and don't have a valid prescription to show for it then well obviously that is a red flag. But if a person shows up with a valid prescriptions and valid diagnoses documented by a legitimate doctor(along with the doctors phone number) and they seem extremely functional then I don't see what the problem is(this includes a valid prescription for medical marijuana).
Some people might argue that giving up their doctors name and phone number is an invasion of privacy(I was a HR manager during college and MANY people had complaints...even asking for a doctors note if they were out sick for a week). But the way I look at it..I have nothing to hide. If my supervisor wants to call my doctor to verify a diagnosis or a medication I am taking then go right ahead...but it is only limited to information needed as to why I need to be on certain schedule II narcotics...not my medical history or other medical problems NOT pertaining to the condition in which I need to be on those medications.
Think about it..Anxiety Disorders are very prevalent and benzos pretty much fly off the shelves these days. Xanax can be impairing as well...but(where I work anyway) if someone is taking a benzo(and only a benzo) they don't have to explain themselves at all.
Then of course acute injuries come into play as well. If someone had a root canal and is on vicodin or something(of course they can hide it if vicodin doesn't do anything to their state of mind) they are encouraged to take time off until the acute pain is resolved and opiates are no longer needed. But of course I am sure many people show up with acute pain(whether it be muscle spasms in their neck or something not as obvious as say a broken leg) and don't tell anyone while they are taking care of patients while on percocet or something..which IMO can be dangerous if they have never had experience with the medication before. It can be easy to hide(I've done it before at old jobs before going into health care when I've gotten teeth pulled, shoulder sprains etc...I was taking vicodin for the pain and no one had a darn clue). I would never do it of course if someones life was in my hands.
By now I have a tolerance to opiates and they do not effect my state of mind, they just allow me to be a productive member of society(especially at my job). Of course my boss knows all about my medical problems(hell I had surgery at the hospital I work at...my co-workers changed the PCA meds for me when they ran out). I really have no shame in my chronic pain...of course everyone is different and may not have the same views as I do.