Paroxetine 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
Paroxetine
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.
Taking amitriptyline (Elavil) and paroxetine (Paxil) together can cause a few things to add up. Paroxetine slows down a liver enzyme (called CYP2D6) that normally breaks down amitriptyline, so amitriptyline can build up higher than expected in your body. That can mean more side effects like drowsiness, dry mouth, dizziness, or effects on your heart rhythm.
Both medicines also raise serotonin, so together there is a higher chance of a reaction called serotonin syndrome (things like agitation, sweating, shaking, fast heartbeat, or confusion). The good news is your care team can manage this by adjusting your dose and watching you more closely. Keep taking both as prescribed and talk with your doctor or pharmacist.
Interaction: Combined use raises three overlapping risks: additive QT prolongation, additive serotonergic effects (serotonin syndrome), and increased amitriptyline exposure.
- Mechanism: Paroxetine is a potent CYP2D6 inhibitor; amitriptyline is a CYP2D6 substrate, so its Cmax/AUC rise (desipramine data showed ~2-fold and ~5-fold increases). Both agents are serotonergic and QT-prolonging.
- Direction: Increased amitriptyline (active drug) effect and toxicity.
- Evidence/onset: Theoretical; onset unspecified, highest risk at initiation or dose escalation.
- Management: Coadminister cautiously; monitor for serotonin syndrome, consider ECG in at-risk patients, and reduce the CYP2D6 substrate dose if needed. Re-titrate upward if paroxetine is stopped.
What happens
Increased risk of QT interval prolongation, an increased risk of serotonin syndrome and an increased CYP2D6 substrate exposure
Interaction Deep Dive
Use caution when administering PARoxetine, which inhibits CYP2D6, together with serotonergic CYP2D6 substrates that also prolong the QT interval. During combined therapy, watch for signs of serotonin syndrome, particularly when starting treatment or raising the dose, and if such symptoms develop, promptly stop both PARoxetine and any other serotonergic medications. A reduced dose of the CYP2D6 substrate may be necessary, given that adding PARoxetine to an established regimen produced 2-fold and 5-fold increases in the Cmax and AUC, respectively, of a single dose of desipramine (a CYP2D6 substrate). On the other hand, if PARoxetine is stopped, the dosage of a CYP2D6 substrate may need to be raised. PARoxetine has additionally been linked to ventricular tachycardia and torsade de pointes, and giving it alongside other QT prolonging agents may heighten the risk of QT interval prolongation1.
Why it happens (mechanism)
Additive QT interval prolongation; additive serotonergic effects; inhibition of CYP2D6 substrate metabolism by PARoxetine
How to manage this interaction
This combination can be used, but your care team will usually take a few sensible steps:
- Your amitriptyline dose may need to be adjusted and individualized by your team, since paroxetine can raise its levels.
- They may monitor you more closely, especially when starting either drug or changing a dose, and may check your heart rhythm (ECG).
- If paroxetine is later stopped, your amitriptyline dose may need to be increased again.
Keep taking both as prescribed. Contact your prescriber or pharmacist right away if you notice agitation, sweating, tremor, fast heartbeat, confusion, fainting, or palpitations.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) After a single 100 mg dose of desipramine (a CYP2D6 substrate) was combined with steady state administration of PARoxetine 20 mg/day, the desipramine Cmax, AUC, and t(1/2) rose by a mean of 2-, 5-, and 3-fold, respectively 1.
Common questions
Can I take Paroxetine and Amitriptyline together?
Paroxetine can raise amitriptyline levels and both add to heart-rhythm and serotonin risks, so your doctor may adjust the dose and monitor you more closely; keep taking both as prescribed and report any concerning symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Paroxetine 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 Paroxetine and Amitriptyline interaction managed?
This combination can be used, but your care team will usually take a few sensible steps: Your amitriptyline dose may need to be adjusted and individualized by your team, since paroxetine can raise its levels. They may monitor you more closely, especially when starting either drug or changing a dose, and may check your heart rhythm (ECG). If paroxetine is later stopped, your amitriptyline dose may… 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 Paroxetine 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 (1)
- Product Information: PEXEVA(R) oral tablets, paroxetine mesylate oral tablets. Sebela Pharmaceuticals Inc (per FDA), Roswell, GA, 2023.
Keep reading about Amitriptyline
Keep reading about Paroxetine
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