My new career will depend on passing a drug test at some point. I take klonopin by a legit RX so I've been told that's OK. I last vaporized weed maybe 3 years ago. I think I should be OK but I'm paranoid.
There is absolutely nothing to be worried about if you used it three years ago. Even if it were detectable through hair, they would not be able to find that out, because in such a long time your hair will get completely changed. You are good to go for testing.