I'm 60 so it wasn't till I was over 40 that SSRIs were developed. I didn't have anxiety as such, more depression with a touch of dread, at intervals all my life. The ADs I tried in my 20's didn't suit me, as they just switched off all feeling, and I preferred to feel something.
I was severely depressed in 1998 and had to leave work because of it. That's when I was first prescribed paroxatine. For me it changed my life, it restored my mood to normal :)
I'm not depressed now, but take a low dose, 20mg a day, just for maintenance.
It's quite common to have feelings of nausea at the start of the course, these should pass. Slight odd feelings in the digestive system are possible too. and to start off with they seemed to make me fart for England
Expect not to really notice much difference in mental state for at least 3 weeks, although it is not uncommon for it to take less than that. So soft-pedal, if he was an employee and not s/e he would be signed off at the moment.
Sometimes there may be sexual side effects. Loss of erection can be treated by the GP with viagra.