Doctors recommended Xanax in the lowest effective dose required for certain treatment. Buy Xanax bars online and use them for generalized anxiety disorder. In the treatment of GAD, take 0.25 mg to 0.5 mg of Xanax bars administered orally three times a day. In the treatment of the panic disorder, use 0.5 mg to 1 mg administered orally once a day in the morning. Your healthcare provider may increase the dose of 1 mg at intervals of every 3 to 4 days.