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Brand: Mellaril
Published 2026-02-15 · Last reviewed 2026-02-22 · 4 references
Content sourced from FDA labeling (DailyMed) and peer-reviewed literature.
Thioridazine is a low-potency phenothiazine FGA with prominent anticholinergic effects. It is distinguished clinically by a dose-related risk of QTc prolongation and torsades de pointes–type arrhythmias (label).
Due to its proarrhythmic risk, labeling restricts thioridazine to schizophrenia patients who have not responded to, or cannot tolerate, other antipsychotics (label).
The label highlights multiple contraindications (congenital long QT syndrome, history of arrhythmias, uncorrected hypokalemia, and combinations with other QT-prolonging drugs) and describes avoiding CYP2D6 inhibition that can raise exposure and QT risk (label).
The label recommends baseline ECG and potassium assessment and states that patients with QTc >450 msec should not receive thioridazine (label).
The thioridazine compare view, evidence feed, and print page support evaluation of lower-QT alternatives.
Thioridazine is generally treated as a last-line oral antipsychotic because of QT-related risks and extensive contraindicated drug interactions. When used, the care plan is typically ECG-anchored with a strong emphasis on interaction screening (label/clinical).
View labelExactRefer to the Glossary entry on Neurotransmitters for background on receptor systems involved in serious mental illness.
Dopamine D2 receptor antagonism is the primary antipsychotic mechanism.
Anticholinergic activity contributes to dry mouth, constipation, and urinary retention risk.
QT prolongation is a key safety issue and is described as dose-related in labeling.