"i have been taking xanax off and on for about 3 years now. it is great for anxiety. i spent thousands of dollars going to the er thinking i was having a heart attack before it was brought to my attention that it was actually anxiety. i take 0.5mg as needed now. i noticed that when i stopped taking it that i could not sleep for days and i became shaky at times, and the anxiety returns immediately. the other thing that i notice is that after a while you become immune to the dosage. if you only take it with the onset of an anxiety or panic attack it shouldn&#039;t be a problem."