Lidoflazine and Amitriptyline: 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
Lidoflazine
No brand names on record
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 these medicines can affect your heart's rhythm. Amitriptyline (Elavil), an older antidepressant, and lidoflazine can each stretch out a part of your heartbeat called the QT interval. When you take them together, that effect can add up and make dangerous, irregular heartbeats more likely.
I want to be honest: this is based on how the drugs work, not on studies of people taking both. Still, because heart rhythm problems can be serious, this combination is generally not recommended. Please don't stop either medicine on your own. Talk with your doctor or pharmacist so they can pick the safest plan for you.
Mechanism: Additive QTc prolongation. Both amitriptyline (a TCA) and lidoflazine independently prolong the QT interval at therapeutic doses, raising the risk of torsades de pointes and cardiac arrest. Neither is a prodrug relevant here; this is a pharmacodynamic (not PK) interaction.
- Direction: Additive proarrhythmic effect (increased cardiotoxicity risk).
- Evidence: Theoretical; no formal interaction studies.
- Onset: Unspecified.
- Management: Concurrent use is not recommended. If unavoidable, obtain baseline and follow-up ECGs, monitor QTc, correct electrolytes (K+, Mg2+), and consider an alternative agent.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
At the doses recommended for therapy, both lidoflazine and tricyclic antidepressants (TCAs) have demonstrated the ability to lengthen the QTc interval21. Although no formal studies examining this drug interaction have been conducted, giving TCAs together with lidoflazine or other agents recognized to prolong the QTc interval is advised against3.
Why it happens (mechanism)
Additive effects on QT prolongation
How to manage this interaction
The main message: this combination is generally not recommended. Because both drugs can stretch the QT interval, your care team will usually look for a safer option rather than use them together.
- Keep taking both medicines exactly as prescribed until your prescriber tells you otherwise. Do not stop on your own.
- Let your doctor and pharmacist know you are taking both so they can review whether an alternative is better for you.
- Your team may check your heart rhythm (ECG) and monitor you more closely if you do need both.
- Get urgent help for fainting, palpitations, or a racing, irregular heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Lidoflazine and Amitriptyline together?
Amitriptyline and lidoflazine both prolong the QT interval, and using them together raises the risk of serious heart rhythm problems, so this combination is generally not recommended. Talk with your prescriber or pharmacist about a safer option. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lidoflazine and Amitriptyline 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 Lidoflazine and Amitriptyline interaction managed?
The main message: this combination is generally not recommended. Because both drugs can stretch the QT interval, your care team will usually look for a safer option rather than use them together. Keep taking both medicines exactly as prescribed until your prescriber tells you otherwise. Do not stop on your own. Let your doctor and pharmacist know you are taking both so they can review whether an 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 Lidoflazine or Amitriptyline 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 (3)
- 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
- Hanley SP & Hampton JR: Ventricular arrhythmias associated with lidoflazine: side effects observed in a randomized trial. Eur Heart J 1983; 4:889-893. PubMed
- Product Information: Elavil(R), amitriptyline. Merck & Co, Inc, West Point, PA, 1999. DailyMed
Keep reading about Amitriptyline
Keep reading about Lidoflazine
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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