Clarithromycin and Propafenone interaction
Clarithromycin and Propafenone: 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 Clarithromycin label · effective 2026-01-01
QT Prolongation : Avoid clarithromycin tablets in patients with known QT prolongation or receiving drugs known to prolong the QT interval, ventricular arrhythmia ( torsades de pointes ), hypokalemia/hypomagnesemia, significant bradycardia, or taking Class IA or III antiarrhythmics ( 5.2 )
…Interactions with Clarithromycin Tablets Drugs That Are Affected By Clarithromycin Tablets Drug(s) with Pharmacokinetics Affected by Clarithromycin Tablets Recommendation Comments Antiarrhythmics: Disopyramide Quinidine Dofetilide Amiodarone Sotalol Procainamide Not Recommended Disopyramide, Quinidine: There have been postmarketing reports of torsades de pointes…
…known to prolong the QT interval [see also Contraindications ( 4.2 )] • patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia,clinically significant bradycardia and in patients receiving Class IA (e.g., quinidine, procainamide,disopyramide) or Class III (e.g., dofetilide, amiodarone, sotalol) antiarrhythmic agents.
From the Propafenone (propafenone hydrochloride) label · effective 2026-01-29
• Avoid use with other antiarrhythmic agents or drugs that prolong the QT interval.
• Avoid simultaneous use of propafenone with both a cytochrome P450 2D6 (CYP2D6) inhibitor and a 3A4 inhibitor (CYP3A4).
Therefore, avoid simultaneous use of propafenone hydrochloride extended-release capsules with both a CYP2D6 inhibitor and a CYP3A4 inhibitor.
Therefore, simultaneous use of propafenone hydrochloride extended-release capsules with both a CYP2D6 inhibitor and a CYP3A4 inhibitor should be avoided [see Warnings and Precautions ( 5.4 ) and Dosage and Administration ( 2 )].
It may also worsen premature ventricular contractions or supraventricular arrhythmias, and it may prolong the QT interval.
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.