Antihistamine

[Marquetta]

a type of drug that is used to treat medical conditions caused by an extreme reaction to particular substances:

[Tina]

a drug taken to limit the bad effect of the body’s reaction to some substances:

[Oralee]

It’s just a play on words that his [pockets] are “[stuffy]” (stuffed with cash), and the irony of the reference to antihistamine which would clear up [a stuffy] nose, but clearly has nothing to do with pockets stuffed with cash.