Amitriptyline and Tetrabenazine: 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
Tetrabenazine
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 amitriptyline (a medicine often used for depression or nerve pain) and tetrabenazine (used for certain movement disorders) can affect the electrical timing of your heartbeat. Doctors call this the QT interval. When two medicines that both do this are taken together, the effect can add up and, in rare cases, raise the risk of a dangerous irregular heartbeat.
The good news is this is a known concern your care team can plan around. Please don't stop either medicine on your own. Instead, check in with your pharmacist or doctor so they can decide the safest option for you and watch you more closely if needed.
Effect: Additive QT interval prolongation with increased risk of serious cardiac arrhythmias (e.g., torsades de pointes).
Mechanism: Both agents independently prolong the QT interval; concurrent use produces additive pharmacodynamic effects. This is a PD interaction, not enzyme- or transporter-mediated. Neither activation issue applies.
- Direction: Additive QT prolongation.
- Onset: Unspecified.
- Evidence: Theoretical.
- Severity: Major.
Management: Avoid concomitant use where possible. If unavoidable, obtain baseline and follow-up ECGs, correct electrolytes (K+, Mg2+), and consider alternatives. Dose should be individualized by the care team with closer cardiac monitoring.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Concurrent administration of amitriptyline with tetrabenazine should be avoided, since the combination may produce additive QT interval prolongation and heighten the likelihood of serious cardiovascular effects1.
Why it happens (mechanism)
Additive effects on the QT interval
How to manage this interaction
Your care team's main goal is to protect your heart rhythm. Here is what they typically consider:
- Avoiding the combination when a safer alternative exists.
- Closer monitoring if both are needed, which may include heart tracings (ECGs) and blood tests to check minerals like potassium and magnesium.
- Individualizing doses, which your team can adjust and tailor to you.
What you should do: keep taking both exactly as prescribed unless told otherwise, and let your pharmacist or doctor know you are on both. Report any fainting, dizziness, palpitations, or a racing or irregular heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amitriptyline and Tetrabenazine together?
Amitriptyline and tetrabenazine can each stretch the heart's QT interval, and together the risk adds up, so this combination is generally avoided. Talk with your pharmacist or doctor before making any changes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Tetrabenazine 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 Tetrabenazine interaction managed?
Your care team's main goal is to protect your heart rhythm. Here is what they typically consider: Avoiding the combination when a safer alternative exists. Closer monitoring if both are needed, which may include heart tracings (ECGs) and blood tests to check minerals like potassium and magnesium. Individualizing doses, which your team can adjust and tailor to you. What you should do: keep taking b… 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 Tetrabenazine 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 (1)
- Product Information: XENAZINE(R) oral tablets, tetrabenazine oral tablets. Lundbeck Inc. (per FDA), Deerfield, IL, 2011. DailyMed
Keep reading about Amitriptyline
Keep reading about Tetrabenazine
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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