Can you work productively on pain killers?

Tweet

We were super busy today at work, so we called in the new(ish) girl - who had gotten an infected wisdom tooth extracted about a week before. She was inebriated.. from Vicodin when she came in. Seriously. So bad that she couldn't concentrate on anything that she was doing, and did not get even a LITTLE bit of work done. She was also feeling sick and like she was going to throw up. She is like TINY, though - probably like 90 pounds and 5'3 or something. The weird thing is, is that I used to be prescribed pain killers (the same kind) for really bad cramps. And although it made me sleepy sometimes, it never affected my work or my productivity, or even things like eye-sight. It never affected me that way. Now, granted, I'm 5'9 and almost twice her weight! So that could be it, too. It also could be a different dosing. How do you react to painkillers? Is what she was experiencing NORMAL? Can you work when you're taking pain killers?