I take dexedrine and find myself only able to study when i am on xanax (alprazolam) >4mg. i'm not abusing it. it helps me study for school. is this uncommon?

Who is prescribing?: I'm wondering whether you're working with a psychiatrist? With this combination of medicines you really need to be. You don't state the amount of Dexedrine you're taking, but that one in particular has a high potential for habituation and abuse. Also routinely taking >4mg of xanax (alprazolam) to "study" is a very high dose which in the long run is addictive. It's also "uncommon" to use in this way.