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How long does Xanax last for / stay in your system?

Medically reviewed by Carmen Pope, BPharm. Last updated on Jan 20, 2025.

Official Answer by Drugs.com

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. However, the calming, relaxing, and sedative effects of Xanax usually wear off within about eight to twelve hours.

Xanax is taken by mouth and quickly absorbed into the bloodstream. Effects should be noticed within an hour and the medicine reaches peak concentrations in the body after one to two hours. People who take Xanax regularly can build up a tolerance to it and effects, such as a feeling of calm or sedation, may take longer to develop or not be felt as strongly as before.

Xanax is usually prescribed three times a day because its effects in the body (calming, sedation, relaxing) tend to wear off within eight hours for most people. However, one dose of Xanax remains detectable in the body for two to five days – the exact length of time depends on several factors specific to the individual who took the dose.

What factors determine the half-life of Xanax?

Factors that determine how long a dose of Xanax will persist in the body for include:

Related questions

How long does Xanax stay in your system?

Studies have shown that the half-life of Xanax ranges from 6.3 to 26.9 hours. It is important to realize that half-life is a figure that is an estimate of the time it takes for the concentration or amount in the body of that drug to be reduced by exactly one half (50%). After four to five half-lives, 97% of a drug has cleared from the body, and the drug is no longer considered to be having any effect. However, this does not mean that it won’t be detectable by a drug test, as this depends on how specific and sensitive the drug test is.

If we use the average half-life of Xanax, which is 11.2 hours, then the following is estimated for a 1mg dose of Xanax:

In theory, we can see that after 56 hours (2.3 days), almost all the original Xanax dose (slightly less than 97%) has been eliminated in people whose Xanax half life is 11.2 hours. However, in some people, the half-life of Xanax is 26.9 hours. In these people, it will take approximately 134.5 hours (5.6 days) for almost 97% of a dose of Xanax to be eliminated.

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