Why did Mucinex DM make me high?

Some patients have an exaggerated sensitivity to certain drugs or drug components. If you ever took it again, you would need to have someone at home to keep you safe, and I suggest you use only the Mucinex without the Dextromethorphan component. In fact, break the Mucinex plain tablet in half. I am not quite as sensitive as you to this, but I find that a half a Mucinex tablet with lots of water throughout the day works as well for me as a higher dose, without the "slightly unreal feeling" which I positively cannot have while working. Best wishes.