how long do the affects of xanax last?

[warmduck]

what is the half life, lets say you take 1.5mg

and what is the come up, the peak, etc

 

[kosmokramer]

Here is a summary from Erowid.
They are a very useful resource. There is also several threads here with the same information.


EFFECTS :
Primary effects include euphoria, drowsiness, sedation, a decrease in social inhibitions, and intense relaxation.

Onset :
Effects are generally felt 20-40 minutes after oral ingestion (faster via sublingual), although it can take up to an hour to feel the full effects.

Duration :
Alprazolam is considered a "short-acting" benzodiazepine. Users report that the effects of the drug last from 2 to 6 hours with lingering after-effects of several more hours.

Hope this answers your question.