I've been taking pristiq (desvenlafaxine) for almost a month and everytime i take it i get nauseated and i can't sleep. so i'm up all night what could it be?

Pristiq (desvenlafaxine): That is not uncommon for some to respond that way to pristiq (desvenlafaxine). Review other alternatives with your prescribing doc.

Anxiety: Nausea can be a common side effect of many antidepressants, but that ought to go after a few days to a week. If your anxiety or depression is not being treated adequately, you may have some acid reflux, you should discuss the possibility of increasing your dose or looking at alternative medications.