Xanax lost its effect on me and was actually helpful when it worked (0,375 mg in total now). But there's the psychological addiction thing that worries me when I recommend it. And yes, be very careful of serotonin syndrome. Start very slow and be mindful of your symptoms, please. Hydroxyzine did not work for my anxiety as well, by the way.
Ozgun, I don't think there is any chance of Serotonin Syndrome , as my GP won't agree to a cross taper.