thioridazine

General information

• Class: Antipsychotic
• Common US brands: Mellaril
• Typical dose range: The label emphasizes determining the smallest effective dose for each patient due to QT risk and restricting use to schizophrenia after failure of other agents (label).
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2026-02-22

Dosing & forms

• Forms/strengths: Tablets: 10 mg, 25 mg, 50 mg, 100 mg (label/manufacturer-dependent).
• Frequency: Adult schizophrenia dosing: label describes a usual starting dose of 50–100 mg three times daily with gradual titration as needed (label).
• Typical range: The label emphasizes determining the smallest effective dose for each patient due to QT risk and restricting use to schizophrenia after failure of other agents (label).

Mechanism (brief)

Low-potency phenothiazine first-generation antipsychotic (D2 antagonism) with prominent anticholinergic effects. Notable for dose-related QTc prolongation risk; labeling restricts use to schizophrenia after failure of other agents.

Metabolism & Half‑life

• Metabolism: CYP2D6
• Half‑life: —

Therapeutic Drug Monitoring (TDM)

Recommended: No

Monitoring highlights

• Baseline ECG and potassium; consider periodic ECG/potassium during titration (label).
• Avoid QT-prolonging combinations; re-check medication list after any new prescription.
• Sedation, orthostasis, and anticholinergic effects (falls and delirium risk).
• Movement symptoms and tardive dyskinesia screening.
• Palpitations, presyncope/syncope, or new dizziness prompt urgent reassessment (label/clinical).

Sources

• Thioridazine hydrochloride tablets prescribing information — DailyMed (2025)
• Torsade de Pointes (StatPearls) — StatPearls Publishing (NCBI Bookshelf) (2025)
• The American Psychiatric Association Practice Guideline for the Treatment of Patients With Schizophrenia — American Psychiatric Association (2020)
• AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology — Pharmacopsychiatry (2018)