When comparing Xanax vs Ativan, both belong to the benzodiazepine class of medications and are commonly prescribed to treat anxiety, panic disorders, and insomnia, but they differ in how they act and how long they last. Xanax (generic name alprazolam) works quickly, offering fast relief from acute anxiety or panic attacks, but its effects wear off sooner usually within 4 to 6 hours. Ativan (generic name lorazepam) takes slightly longer to start working but provides longer-lasting calmness, often up to 8 to 12 hours.