From the FDA Drug Label
Using a specific assay methodology, the mean plasma elimination half-life of alprazolam has been found to be about 11.2 hours (range: 6.3–26. 9 hours) in healthy adults.
The half-life of alprazolam is approximately 11.2 hours with a range of 6.3–26.9 hours in healthy adults 1.
From the Research
The half-life of Xanax (alprazolam) is approximately 11-12 hours in healthy adults, though this can range from 6.3 to 26.9 hours depending on individual factors, as reported in the most recent and highest quality study available 2. This means it takes about 11-12 hours for half of the drug to be eliminated from your body. Complete elimination typically requires 4-5 half-lives, so Xanax generally remains in your system for about 2-4 days. Several factors can affect this timeline including:
- Age
- Liver function
- Weight
- Concurrent medications Older adults and those with liver impairment often experience longer half-lives, potentially up to 26 hours, as noted in studies 3, 4, 5, 6. Xanax's relatively short half-life compared to some other benzodiazepines explains why it may cause more pronounced withdrawal symptoms when discontinued abruptly. This is also why Xanax is typically prescribed for short-term use and may require multiple daily doses to maintain therapeutic effects. If you're taking Xanax, never stop it suddenly as this can trigger potentially dangerous withdrawal symptoms, a precaution supported by the pharmacokinetic profile of the drug 2.