Generic Pristiq (Desvenlafaxine) being an antidepressant drug falls in the category of drugs known as SNRIs (Serotonin and norepinephrine reuptake inhibitors). It is used in the treatment of depressive disorders. This medication is available in the form of tablets and in 4 different strengths. You should buy Pristiq only after validating the benefits and risks of this medication by having a discussion with your health care provider.