I am very surprised to hear that the pharmacist you spoke to didn't know the drug/herb interactions. He/she should have access online to this information. Perhaps you should try another pharama?
I can give you a list, but I don't know for certain that it is complete or up to date. I am using the 2012 Mosby's Nursing Drug Reference.
Xanax should NOT be taken with cat's claw, chamomile, cowslip, echinaces, goldenseal, hops, kava, licorice, Queen Anne's lace, skullcap, St.