Blue Xanax bar is a 2mg dose of Alprazolam active ingredient and a popular anti-anxiety prescription medication, Xanax. It is referred to as the blue pill and has number imprints "B707" and" 2" on the other side of the bar. It contains the active ingredient Alprazolam which works by slowing f down the activity of the central nervous system. As a result, it alters the balance of certain neurotransmitters in the brain and helps reduce anxiety and panic.