Yellow Xanax Bar is a quick-acting antianxiety drug that helps to treat anxiety disorder, panic disorder, and phobia. Yellow Bars are rectangular 2Mg of Alprazolam tablets with the imprint of “R039” on one side of the bar. Due to its color, the street name of Yellow Xanax is “Yellow School Bus” or “Yellow bus.” The 2 mg yellow Xanax bars are designed to be broken in half, allowing for two equal-sized doses in the morning and later in the day. Yellow Xanax works by enhancing the activity and function of certain specific chemicals called neurotransmitters( GABA) to calm the brain and nerve cells and reduce anxiety.