Hi, My Son Is Currently Prescribed Paroxetine 20 Mg. Last

Hi, my son is currently prescribed paroxetine 20 mg. Last night he was out with some friends at a bar/restaurant when he started feeling strangely. He broke out in a sweat and he's feeling anxious along with nausea. He seems to think someone dropped something in his drink. What can he do to reverse a reaction to a possible substance?