Flecainide and Desipramine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Desipramine
Flecainide
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Class I antiarrhythmics have been shown to prolong the QTc interval at the recommended therapeutic dose. Even though no formal drug interaction studies have been done, the coadministration of Class I antiarrhythmics and other drugs known to prolong the QTc interval, including tricyclic antidepressants, is not recommended512.
Why it happens (mechanism)
Additive effects on QT prolongation
Literature reports
2 reports — tap to read
a) EKG effects reported in patients receiving therapeutic doses of tricyclic antidepressants include increased heart rate, prolonged PR interval, intraventricular conduction delays, increased corrected QT interval (QTc) and flattened T waves 3.
b) A 68-year-old man suffering from agitated major depression was begun on a dose of desipramine 125 mg daily which produced a subtherapeutic serum level of 442 nmol/L (therapeutic range = 500 to 1000 nmol/L). An increased dose of 175 mg daily produced excellent clinical response with no side effects. He developed atrial fibrillation and flutter. Digoxin 0.25 mg daily was added to his therapy, and desipramine was discontinued. His arrhythmia was suppressed with the addition of propafenone 150 mg twice daily and 300 mg at bedtime. Desipramine 150 mg daily was again begun, at which point he experienced dry mouth, sedation, and shakiness; the desipramine serum level was measured at 2092 nmol/L. The desipramine was discontinued for five days, the side effects ceased, and desipramine therapy was resumed at 75 mg daily. The desipramine serum level was measured at 1130 nmol/L 4.
Common questions
Can I take Flecainide and Desipramine together?
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Flecainide and Desipramine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Flecainide or Desipramine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (5)
- Larochelle P, Belanger L, Lemire F, et al: Dose-response effect of propafenone in patients with ventricular arrhythmias. Curr Ther Res 1984; 36:959-969. DOI
- Scagliotti D, Strasberg B, Hai HA, et al: Aprindine-induced polymorphous ventricular tachycardia. Am J Cardiol 1982; 49:1297-1300. DOI
- Marshall JB & Forker AD: Cardiovascular effects of tricyclic antidepressant drugs: therapeutic usage, overdose, and management of complications. Am Heart J 1982; 103:401-414. PubMed
- Katz MR: Raised serum levels of desipramine with the antiarrhythmic propafenone (letter). J Clin Psychiatry 1991; 52:432-433.
- Product Information: Tambocor(R) flecainide acetate. 3M Pharmaceuticals, Northridge, CA, 1998.
Keep reading about Desipramine
Keep reading about Flecainide
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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