Donna - I am not a physician but have worked with lots of clients who take alprazolam (aka: Xanax). Xanax is a very effective antianxiety medication but people who have been taking it for some time can become physically dependent on it. Just how much of a problem this will be will depend on the dose, how often it's taken, how long its been taken, and what other medications or drugs are also being taken. When the medication is stopped all of a sudden their body will feel very uncomfortable and they can go through withdrawal symptoms. You should help your sister find a psychiatrist as soon as possible if she has been very unstable since stopping the medication. Fortunately, she is probably through the worst of the physical withdrawal if it has really been 2 months since she last took it. Good luck. Your sister is lucky that you are looking out for her.   Rick Wirtz