Paroxetine and Thioridazine interaction
Paroxetine and Thioridazine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Paroxetine (PAROXETINE HYDROCHLORIDE) label · effective 2026-09-16
Paroxetine HCL CR should not be used in patients receiving medications that can prolong QT interval and are also metabolized by CYP450 2D6,such as thioridazine or pimozide [see Drug Interactions (7),Warnings and Precautions (5.3)].
Concomitant use of pimozide or thioridazine.
Since thioridazine and pimozide given alone produce prolongation of the QTc interval and increase the risk of serious ventricular arrhythmias, the use of Paroxetine HCL CR is contraindicated in combination with thioridazine and pimozide [see Contraindications ( 4 ), Drug Interactions ( 7 ), Clinical Pharmacology ( 12.3 )].
Examples selegiline, tranylcypromine, isocarboxazid, phenelzine, linezolid, methylene blue Pimozide and Thioridazine Clinical Impact Paroxetine HCL CR should not be used in patients receiving medications that can prolong QT interval and are metabolized by CYP450 2D6 such as thioridazine or pimozide (see Contraindications and Warnings and Precautions ) Intervention…
The CYP2D6 inhibitory properties of paroxetine can elevate plasma levels of thioridazine and pimozide.
From the Thioridazine (Thioridazine Hydrochloride) label · effective 2026-03-02
Reduced cytochrome P450 2D6 isozyme activity drugs that inhibit this isozyme (e.g., fluoxetine and paroxetine) and certain other drugs (e.g., fluvoxamine, propranolol, and pindolol) appear to appreciably inhibit the metabolism of thioridazine.
Drug Interactions Reduced cytochrome P450 2D6 isozyme activity, drugs which inhibit this isozyme (e.g., fluoxetine and paroxetine), and certain other drugs (e.g., fluvoxamine, propranolol, and pindolol) appear to appreciably inhibit the metabolism of thioridazine.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.