Detailed dosage guidelines and administration information for Xanax (alprazolam). Includes dose adjustments, warnings and precautions. Medscape - Antianxiety, panic disorder-specific dosing for Xanax, Niravam (alprazolam), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation. Learn about Xanax (alprazolam) dosages, tapering instructions, and FDA boxed warnings regarding addiction and opioid interactions. Xanax is used to treat panic disorder and generalized anxiety disorder. Find out what the recommended dosages are, how to take the drug, and more. One dose of Xanax can last anywhere from 31 hours to 134.5 hours (5.6 days) in the body, depending on factors related to the individual who took it. However, the calming, relaxing, and sedative effects of Xanax usually wear off within about eight to twelve hours. Find patient medical information for Alprazolam (Xanax) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Do not change your dose or stop taking this medicine without checking first with your doctor. Your doctor may want you to gradually reduce the amount you are using before stopping it completely. The typical dosage of Xanax (alprazolam) for anxiety can range from 0.25 to 0.5 mg taken three times a day. Xanax comes in several strengths and forms. Learn about typical doses for anxiety and panic disorder, how doses are adjusted, and how to taper off safely. Key takeaways Doctors typically start alprazolam treatment at low doses between 0.25 milligrams (mg) and 0.5 mg taken three times daily. They then adjust the dosage based on an individual’s needs.