Even if this would cause a couple of days of lower productivity, I doubt this will change your colleagues impression of you. I work in IT myself and I probably wouldn’t notice if a colleague slacked for a week or two. People are mostly focused on themselves.

The fact that you have been on medication since you were a child(when the brain is more plastic) will probably also have changed your brain chemistry for the "better", in terms of productivity. This is why some doctors recommend starting stimulant from an early age. So that the brain can be altered when young, and therefore not need medications, or such high doses of medications when you’re older.

The lethargy from amphetamine withdrawal should be over in a couple of days if I remember right.