Fluoxetine and Haloperidol interaction
Fluoxetine and Haloperidol: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Fluoxetine (Prozac) label · effective 2026-01-08
Use with caution in combination with other drugs that prolong the QT interval ( 4.2 , 5.11 , 7.7 , 7.8 ) 7.1 Monoamine Oxidase Inhibitors (MAOI) [See Dosage and Administration ( 2.9 , 2.10 ), Contraindications ( 4.1 ), and Warnings and Precautions ( 5.2 )] .
Coadministration of fluoxetine with other drugs that are metabolized by CYP2D6, including certain antidepressants (e.g., TCAs), antipsychotics (e.g., phenothiazines and most atypicals), and antiarrhythmics (e.g., propafenone, flecainide, and others) should be approached with caution.
Elevation of blood levels of haloperidol and clozapine has been observed in patients receiving concomitant fluoxetine.
These include specific antipsychotics (e.g., ziprasidone, iloperidone, chlorpromazine, mesoridazine, droperidol,); specific antibiotics (e.g., erythromycin, gatifloxacin, moxifloxacin, sparfloxacin); Class 1A antiarrhythmic medications (e.g., quinidine, procainamide); Class III antiarrhythmics (e.g., amiodarone, sotalol); and others (e.g., pentamidine, levomethadyl…
Antipsychotics: Potential for elevation of haloperidol and clozapine levels ( 7.7 )
From the Haloperidol (Haldol Decanoate) label · effective 2025-11-11
Concomitant use of HALDOL DECANOATE with other products that prolong the QTc interval may result in a greater increase in the QTc interval, and adverse reactions associated with QTc interval prolongation, including torsade de pointes, other serious arrythmias, and sudden death [see Warnings and Precautions (5.2) ].
CYP3A4 and/or CYP2D6 Inhibitors Clinical Impact CYP3A4 and/or CYP2D6 inhibitors increase haloperidol exposure (haloperidol is a CYP3A4 and CYP2D6 substrate) [see Clinical Pharmacology (12.3) ].
Concomitant use of HALDOL DECANOATE and CYP3A4 and/or CYP2D6 inhibitors may increase the risk of haloperidol-associated adverse reactions.
Table 3: Other Clinically Significant Drugs Interactions See www.fda.gov/CYPandTransporterInteractingDrugs for examples of CYP3A4 and/or CYP2D6 inhibitors, CYP3A4 inducers, and CYP2D6 substrates.
CYP2D6 Substrates Clinical Impact Haloperidol is a CYP2D6 inhibitor.
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.