Amitriptyline and Procainamide: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amitriptyline
Procainamide
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.
Both of your medicines can affect the electrical timing of your heartbeat. Amitriptyline (an antidepressant) and procainamide (a heart rhythm medicine) each have effects on the heart, and when taken together those effects can add up. That may raise the chance of an abnormal heart rhythm.
The good news is this concern is mostly theoretical, and your care team can manage it easily. They may check your heart with an ECG and watch how you feel. Let them know if you notice a fast, pounding, or irregular heartbeat, dizziness, or fainting. Please keep taking both medicines as prescribed unless your doctor tells you otherwise.
Additive cardiotoxicity. Both amitriptyline (a TCA) and procainamide (a class IA antiarrhythmic) exert quinidine-like effects on cardiac conduction, prolonging PR, QRS, and QTc. Combined use is pharmacodynamically additive and may increase risk of QT prolongation, torsades de pointes, and cardiac arrest.
- Direction: additive PD effect (not a metabolic/prodrug interaction).
- Evidence: theoretical; severity rated major.
- Onset: unspecified.
- Management: obtain baseline and periodic ECG; monitor PR/QRS/QTc, electrolytes (K+, Mg2+), and clinical signs of arrhythmia. Dose may need to be individualized; consider alternatives if QTc prolongs.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Taking tricyclic antidepressants such as amitriptyline together with class IA antiarrhythmics such as procainamide can heighten the likelihood of cardiotoxicity, because both drug groups produce comparable cardiac effects12. For this reason, observing the patient for signs and symptoms indicating cardiac toxicity while amitriptyline and procainamide are given together may be advisable.
Why it happens (mechanism)
Additive cardiac toxicity
How to manage this interaction
Your care team can manage this combination safely with a bit of extra attention.
- Keep taking both medicines as prescribed unless your doctor changes them.
- Your team may check an ECG (heart tracing) before and during treatment to watch your heart's timing.
- Doses may need to be adjusted and individualized by your care team based on how your heart responds.
- Tell your pharmacist or doctor right away about a racing, skipping, or pounding heartbeat, dizziness, or fainting.
- Mention any other medicines you take, since some can add to this effect.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Among 53 patients with cardiac disease who received amitriptyline, 6 experienced sudden death, compared with 0 of 53 in the control group. The recommendation was that amitriptyline should be avoided in patients with underlying cardiac disease, unless the depression was debilitating and no other medications provided benefit 4. Further studies were carried out that additionally confirmed amitriptyline was linked to a higher incidence of sudden death in patients with preexisting cardiac disease 34.
b) In a placebo controlled study, imipramine 3.5 mg/kg was given daily to seven patients with severe depression, with doses titrated to achieve therapeutic plasma concentrations. Two patients showed premature atrial depolarizations and premature ventricular depolarizations prior to therapy. One patient had 33 premature atrial depolarizations (PAD) and 30 premature ventricular depolarizations (PVD) per hour, which fell to 0.4 PAC and zero PVC per hour while on imipramine. The other patient had 12 PAD and 169 PVD per hour before treatment and 1.8 PAD and 28.1 PVD per hour while on imipramine. The authors further warned that the incidence of cardiotoxicity might rise if tricyclic antidepressants are given together with Type I antiarrhythmics. They also advised that quinidine and procainamide should not be used to treat the arrhythmias resulting from a tricyclic overdose. The resemblances between these agents may worsen the cardiotoxicity 1.
Common questions
Can I take Amitriptyline and Procainamide together?
Taking amitriptyline and procainamide together can add up their effects on your heart's rhythm, so your care team may monitor you with ECGs and adjust doses. Keep taking both as prescribed and report any irregular heartbeat, dizziness, or fainting. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Procainamide 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 is the Amitriptyline and Procainamide interaction managed?
Your care team can manage this combination safely with a bit of extra attention. Keep taking both medicines as prescribed unless your doctor changes them. Your team may check an ECG (heart tracing) before and during treatment to watch your heart's timing. Doses may need to be adjusted and individualized by your care team based on how your heart responds. Tell your pharmacist or doctor right away a… Management is individual — always follow your own care team's guidance.
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 Amitriptyline or Procainamide 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 (4)
- Kantor SJ, Glassman AH, Bigger JT Jr. et al: The cardiac effects of therapeutic plasma concentrations of imipramine. Am J Psychiatry 1978; 135:534-538. PubMed
- Bigger JT, Giardina EG, Perel JM, et al: Cardiac antiarrhythmic effect of imipramine hydrochloride. N Engl J Med 1977; 296:206-208. PubMed
- Moir DC, Crooks J, Cornwell WB, et al: Cardiotoxicity of amitriptyline. Lancet 1972; 2:561-564. PubMed
- Coull DC, Crooks J, Dingwall-Fordyce I, et al: Amitriptyline and cardiac disease. Lancet 1970; 1:590-591. DOI
Keep reading about Amitriptyline
Keep reading about Procainamide
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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