Hello, Welcome to healthcaremagic.com, This is good to know that you are a concerned friend. Yes it is a genuine worry of yours. Xanax have alprazolam as an active ingredient in it. Alprazolam belongs to benzodiazepine group of medications and have a habit forming tendencies. People who take xanax without prescription often develop tendency to take Xanax in overdose and start abusing it, and hence develop dependence syndrome for Xanax. More over if Xanax taken with weed, it can lead to more sedation, enhances the effect of weed and wise versa. Hence i would suggest that you should encourage your friend to consult a specialist in de-addiction, so as to quit both Xanax and weed abuse. Thank you.