Abstract: The descriptive diagnostic model since DSM-III has often led to “cookbook” diagnosis and assumptions of “chemical imbalance” for psychiatric disorders. Pharmaceutical companies have exploited this in their marketing. This includes promoting self-diagnosis with online checklists. Significant overprescribing of psychotropics has resulted. DSM-5 will provide new disorders and broader diagnostic criteria that will likely exacerbate this. Most psychotropic prescribing is done by primary care physicians, who are problematically excluded from DSM-5 field trials and are influenced by industry-funded key opinion leaders who may promote diagnosis of subthreshold cases. More lax criteria will increase diagnosis of subthreshold cases. Expansion of not otherwise specified (NOS) categories can be used to justify off-label promotion. Pediatric bipolar disorder, constructed within the bipolar disorder NOS category, became an “epidemic” in the United States, fuelled by diagnostic upcoding pressures. Disruptive mood dysregulation disorder may similarly cause overdiagnosis and excessive prescribing, as will other new disorders and lower diagnostic thresholds.