hi..i have understood your concerns... u have been given chlorpheniramine [piriton] injection, but you havent mentioned the cause why u have been given the injection? u have been given the tablets also and u have took some on your own... now u have anxiety and panic attacks associated with it..if u have anxiety feeling for the first tiemand that is due to overdose of the drugs ,, then u shudnt continue xanax for long time.. u have to stop xanax and wait and watch that your symptoms recur or not...if your nxiety with panic attacks is recurrent then u have to go for proper psychiatric interview and psychological evaluation..then only one can give you advice for further management of your anxiety disorder.. actually panic attacks and panic disorder are treated with combination of SSRI antidepressant like [paroxetine, sertraline, fluoxetine, escitalopram etc..] in combination with short term use of benzodiazepines like [clonazepam].. u shud avoid taking xanax because although it is good benzo. it has short half life and thats why it is habit forming.. if your anxiety is long lasting then u shud follow following treatment schedule: 1. tablet. paroxetine [paxil 25 mg] once at night. u can increase the dose to 37.5 and then to 50 mg depending upon the response u get from the drug.. 2. tablet klonopin [clonazepam 0.25 mg ] twice daily.. gradually decrease the dose after 1 mnth and stop within next one mnth. 3. u can take tablet. zolpidem [ambien 10 mg ] at night for sleep disturbance.. i hope u ll find this advice helpful...best luck..