Fluoxetine and Pimozide interaction
Fluoxetine and Pimozide: 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 Fluoxetine (Prozac) label · effective 2026-01-08
Other Contraindications The use of PROZAC is contraindicated with the following: Pimozide [see Warnings and Precautions ( 5.11 ) and Drug Interactions ( 7.7 , 7.8 )] Thioridazine [see Warnings and Precautions ( 5.11 ) and Drug Interactions ( 7.7 , 7.8 )] Pimozide and thioridazine prolong the QT interval.
PROZAC can increase the levels of pimozide and thioridazine through inhibition of CYP2D6.
Pimozide and thioridazine are contraindicated for use with PROZAC.
Drugs that Prolong the QT Interval: Do not use Prozac with thioridazine or pimozide.
From the Pimozide label · effective 2026-08-12
Because pimozide prolongs the QT interval of the electrocardiogram it is contraindicated in patients with congenital long QT syndrome, patients with a history of cardiac arrhythmias, patients taking other drugs which prolong the QT interval of the electrocardiogram or patients with known hypokalemia or hypomagnesemia (see also PRECAUTIONS - DRUG INTERACTIONS ).
Concomitant use of pimozide with paroxetine and other strong CYP 2D6 inhibitors is contraindicated (See PRECAUTIONS – DRUG INTERACTIONS ).
Concomitant use of pimozide and paroxetine or other strong CYP 2D6 inhibitors are contraindicated (see CONTRAINDICATIONS ).
Rare case reports have suggested possible additive effects of pimozide and fluoxetine leading to bradycardia.
DRUG INTERACTIONS Because pimozide prolongs the QT interval of the electrocardiogram, an additive effect on QT interval would be anticipated if administered with other drugs, such as phenothiazines, tricyclic antidepressants or antiarrhythmic agents, which prolong the QT interval.
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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.