Flecainide and Ritonavir interaction
Flecainide and Ritonavir: 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 Ritonavir (Norvir) label · effective 2026-07-23
WARNING: DRUG-DRUG INTERACTIONS LEADING TO POTENTIALLY SERIOUS AND/OR LIFE THREATENING REACTIONS Co-administration of NORVIR with several classes of drugs including sedative hypnotics, antiarrhythmics, or ergot alkaloid preparations may result in potentially serious and/or life-threatening adverse events due to possible effects of NORVIR on the hepatic metabolism…
…AND/OR LIFE THREATENING REACTIONS See full prescribing information for complete boxed warning Co-administration of NORVIR with several classes of drugs including sedative hypnotics, antiarrhythmics, or ergot alkaloid preparations may result in potentially serious and/or life-threatening adverse events due to possible effects of NORVIR on the hepatic metabolism…
…and/or life-threatening reactions [see Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] . ○ Alpha 1- Adrenoreceptor Antagonist: alfuzosin ○ Antianginal: ranolazine ○ Antiarrhythmics: amiodarone, dronedarone, flecainide, propafenone, quinidine ○ Antifungal: voriconazole ○ Anti-gout: colchicine ○ Antipsychotics: lurasidone, pimozide ○ Ergot Derivatives:…
Antiarrhythmics: amiodarone, dronedarone, flecainide, propafenone, quinidine ↑ antiarrhythmics Contraindicated due to potential for cardiac arrhythmias [see Contraindications ( 4 ) ] .
Antiarrhythmics: disopyramide, lidocaine, mexiletine ↑ antiarrhythmics Caution is warranted and therapeutic concentration monitoring is recommended for antiarrhythmics when co-administered with ritonavir, if available.
From the Flecainide (Flecainide Acetate) label · effective 2026-02-06
Limited data in patients receiving known enzyme inducers ( phenytoin, phenobarbital, carbamazepine ) indicate only a 30% increase in the rate of flecainide elimination.
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.