How is possible that general practitioners are allowed to prescribe psychiatric drugs?

MDs can rx all meds. Us physicians may legally prescribe almost any med without regard to specialty. In theory i could rx chemotherapy even though i've never practiced oncology. I could even perform surgery if a hospital were foolish enough to allow it. Primary care docs are in a much better position, & usually rx antidepressants & anti-anxiety meds well. For anything more complex, see a psychiatrist.
Within Their Scope. Prozac (fluoxetine), (fluoxetine) released in1987, started a revolution in the writing of prescriptions for psychiatric medications. Prozac (fluoxetine) was much safer to use than its predecessors, better side effect profile, less lethal in overdose. Primary care physicians began prescribing this and like meds in record numbers. Today primary care physicians are trained in their use and taught when a psychiatric referral is necessary.