I heard, and not sure how true this is, it can interfere with a LOT of stuff.... that it should almost be considered like an MAOI, and you know the warnings on everything about those....
This is gonna sound silly, but there's a tea from Celestial Seasonings called Tension Tamer.... when I drink it regularly it truly makes a difference, honestly. In fact there's a 'boost' from Jamba Juice....Femme Boost.... loaded with B vitamins, that also does the same mood calming thing. So maybe it's the B Vitamins, maybe it's the placebo effect.
In any event, good luck to you, and I hope you find something that works for you. I deal with anxiety and it truly, truly sucks.