Is it common to feel drugged up when you eat something to which you are allergic or sensitive?

Not usually: An allergic reaction to a food is usually more dramatic. I believe a high-carb diet is more likely to make you feel drugged up especially after lunch when your circadian cycle catches up with you. That' s why in many mediterranean countries, siesta time was often practiced although no longer common with global competition. Some would say that a high tryptophan meat would also make you.