What is a significant side effect of Thioridazine (Mellaril) that requires cardiac monitoring?

Thioridazine, an antipsychotic medication, is known for its potential to cause QT prolongation, which is a significant concern that necessitates cardiac monitoring. QT prolongation refers to an extended interval between the Q and T waves on an electrocardiogram (ECG), which can predispose patients to serious arrhythmias, including Torsades de Pointes, a potentially life-threatening condition. Because of the risk associated with QT prolongation, healthcare providers are advised to monitor the cardiac status of patients taking Thioridazine, especially in those with pre-existing heart conditions, electrolyte imbalances, or who are taking other medications that can also prolong the QT interval.

Excessive sedation, while a possible side effect, is not as critical in requiring cardiac monitoring compared to QT prolongation. Neutropenia and weight gain are other side effects associated with various antipsychotics but do not present the same immediate cardiac risk that necessitates vigilant monitoring. Hence, the cardiac implications of QT prolongation make it the most significant side effect requiring attention in the context of Thioridazine treatment.