Amitriptyline and Crizotinib: 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
Crizotinib
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 mood, pain, or sleep) and crizotinib (a cancer medicine) can affect the timing of your heartbeat. This is called QT prolongation. When two medicines that both do this are taken together, the effect can add up and, in rare cases, lead to an irregular heartbeat.
This concern is mostly based on how these drugs work rather than a lot of real-world cases, but it's still worth taking seriously. The good news is your care team can manage this well by checking your heart with an ECG and watching your blood levels of things like potassium and magnesium. Please don't stop either medicine on your own, just talk with your doctor or pharmacist.
Effect: Additive QT/QTc interval prolongation with concurrent amitriptyline (a TCA with known QT effects) and crizotinib (labeled for QTc prolongation). Neither is a prodrug here; this is a pharmacodynamic, not pharmacokinetic, interaction.
Direction: Increased combined risk of QTc prolongation and, potentially, torsades de pointes.
Evidence: Theoretical; severity major; onset unspecified.
- Avoid concomitant use where feasible.
- If combined, monitor baseline and periodic ECGs and correct electrolytes (K+, Mg2+, Ca2+).
- Withhold, dose-reduce, or discontinue crizotinib for significant QTc prolongation per labeling.
- Account for other QT-prolonging agents, bradycardia, and hepatic/renal status.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Because crizotinib is linked to QT/QTc interval prolongation, its simultaneous use with another agent that prolongs the QT interval should be avoided, since the prolonging effects may be additive. When the two are used together, monitor ECGs and electrolytes. Depending on clinical circumstances, crizotinib may need to be withheld, dose-reduced, or stopped permanently in cases of QT/QTc interval prolongation1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Your care team can manage this safely. Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise.
- Your team may avoid using them together when possible, or watch you more closely if both are needed.
- Expect ECGs (heart tracings) and blood tests to check electrolytes like potassium and magnesium.
- Your crizotinib dose may be adjusted, paused, or changed by your team based on your heart tracings.
Tell your pharmacist or doctor about any fainting, dizziness, palpitations, or an irregular heartbeat, and mention all other medicines you take.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amitriptyline and Crizotinib together?
Taking amitriptyline and crizotinib together can add up their effects on your heart rhythm (QT prolongation), so your care team may avoid the combination or monitor your ECG and electrolytes closely. Do not stop either drug on your own; raise any dizziness, fainting, or palpitations with your doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Crizotinib 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 Crizotinib interaction managed?
Your care team can manage this safely. Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise. Your team may avoid using them together when possible, or watch you more closely if both are needed. Expect ECGs (heart tracings) and blood tests to check electrolytes like potassium and magnesium. Your crizotinib dose may be adjusted, paused, or changed by your team base… 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 Crizotinib 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: XALKORI(R) oral pellets, oral capsules, crizotinib oral pellets, oral capsules. Pfizer Labs (per FDA), New York, NY, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Crizotinib
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist