Xanax has a relatively short half-life of 11-12 hours compared to other benzodiazepines, which contributes to its quick onset and shorter duration of effects. For example, older adults or those with impaired liver function may experience a longer half-life, meaning Xanax stays in their system longer. Xanax starts working for everyone and produces calming effects to relieve anxiety and panic within an hour of taking an initial dose. However, it may take longer to show its effects in some people. Xanax works fast but doesn’t last long. Learn how its half-life affects dosing, why effects fade before the drug leaves your body, and what influences how long… Learn how long Xanax lasts, including its therapeutic effects, the length of a Xanax high, and what to expect from Xanax withdrawal. On average, the half-life of Alprazolam (Xanax) has an elimination of about 11 hours (though the range is from about 6-27 hours—sometimes higher in obese patients). Xanax should fully clear the body in less than four days for most healthy individuals. However, there are a number of factors that could alter the time it takes for Xanax to clear the body. The duration of action of Xanax can vary depending on factors such as dosage and individual metabolism. Generally, the effects of a single dose of Xanax last for about 4 to 6 hours in most individuals. Xanax’s effects can be felt quickly, within 30 minutes to an hour, but wear off after about six hours, requiring multiple daily doses. Despite a shelf life of two to three years, factors like storage conditions and specific formulations can affect Xanax’s potency. Find out how long does the Xanax effect last for immediate-release and extended-release versions. Learn about half-life, affecting factors, and safety precautions. Xanax (alprazolam) is a medication used to treat anxiety and panic disorders. 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.