On February 15, 1954, the U.S. Food and Drug Administration approved chlorpromazine (marketed as Thorazine in the United States) for use in psychiatric disorders, representing the first regulatory approval of what came to be called an antipsychotic drug. Chlorpromazine had been developed earlier in the 1950s by chemists at the French pharmaceutical company Rhône-Poulenc; its sedative and antipsychotic properties were recognized in clinical settings beginning around 1952. The 1954 FDA approval was a pivotal moment in psychiatric medicine because it provided a pharmacological alternative to the primarily custodial and often long-term institutional care that had dominated treatment for schizophrenia and other severe psychoses. Clinical impact and practice changes Chlorpromazine produced clearer reductions in agitation, hallucinations and delusions for many patients than available sedatives and electroconvulsive therapy alone. Its introduction helped make possible shorter hospital stays, increased use of outpatient management, and the eventual deinstitutionalization movement in the United States and elsewhere. Physicians and hospitals adopted the drug widely in the 1950s, and it became a prototype for a new class of treatments that would be called typical (first-generation) antipsychotics. Pharmacology and side effects Chlorpromazine works primarily by antagonizing dopamine D2 receptors, which is associated with reductions in positive psychotic symptoms for many patients. However, it also produces a range of side effects: common acute effects include sedation and anticholinergic symptoms; long-term or higher-dose use can cause extrapyramidal symptoms (drug-induced movement disorders) and, in some cases, tardive dyskinesia, a sometimes persistent involuntary movement disorder. Over subsequent decades, recognition of these adverse effects drove efforts to develop drugs with different profiles and to refine dosing and monitoring practices. Broader social and medical consequences The FDA approval symbolized a broader transformation in psychiatry from primarily custodial care to treatments emphasizing symptom control and community-based management. While chlorpromazine and related drugs improved outcomes for many patients, the transition also revealed systemic challenges: inadequate community mental health infrastructure, inconsistent access to ongoing care, and variable outcomes for different patient groups. Debates about overreliance on medication, informed consent, and the balance between pharmacological and psychosocial treatments emerged and continue to inform psychiatric practice. Legacy and evolution Chlorpromazine remained widely used through the mid-20th century and provided the template for numerous subsequent antipsychotic drugs. In the 1970s and later, research produced new antipsychotics with different side-effect profiles (often termed atypical or second-generation antipsychotics), though debates about efficacy and safety persist. Historically, the 1954 FDA approval is remembered as a turning point: it inaugurated pharmacological treatment of psychosis on a large scale and reshaped clinical, institutional, and social approaches to severe mental illness. Notes on sources and uncertainties The development timeline—French research and clinical use in the early 1950s followed by U.S. marketing and the FDA approval in 1954—is supported by historical medical literature. Specific clinical practice changes and societal effects varied by country and region, and outcomes depended heavily on the presence or absence of community services; those local variations are not fully captured here.