> I was noticing the other day how my pollen allergies would subside when I took some Adderall, and would come back when it wore off.

The explanation is much more simple: Adderall is amphetamine, which has functional overlap with how pseudoephedrine (aka Sudafed) works. They are both norepinephrine releasing agents.

Pseudoephedrine is considered a substituted amphetamine in chemistry lingo.