Hello, hopefully I can help you out. The maximum dosage for xanax is about 10mg a day. This is a large dose, as a common starts at 0.5mg 3 times a day. If your friend is taking more than this, or combining it with alcohol, it is grounds for concern. Signs and symptoms to watch out for are respiratory depression (slowed breathing), confusion, coma, sleepiness, slowed reaction time.
So if you can, find out about how much he/she is taking, and if it is 10mg or more a day, that is considered more than a normal prescribed dose, or if there is alcohol involved, both of these scenarios can be fatal.
Obviously there are other factors that can be involved such as the size of the person, tolerance, other medications, etc, but hopefully this will provide you with a ballpark figure, best of luck...
Please ask if you need clarification/more information.
If I have answered your question, please click the accept button
POSITIVE feedback & a BONUS are greatly appreciated. Please note that answers are for information only, do not take the place of an assessment by your doctor, and does not establish a patient-physician relationship