Xanax is a prescription medicine used for treating anxiety. works by lessening abnormal excitement in the brain. It is a class of drugs. Is called benzodiazepines.calms your nervous system. works by lessening abnormal excitement in the brain and the effects of certain natural chemicals in the body. Not taking it more time may cause serious side effects including depressed mood, confusion, and agitation. Xanax is available in 1mg,2mg,3mg, and 0.5mg.