Amitriptyline and Levomilnacipran: 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
Levomilnacipran
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 amitriptyline and levomilnacipran raise serotonin, a natural brain chemical that affects mood. Taken together, they can push serotonin levels too high, which in rare cases leads to a reaction called serotonin syndrome.
Signs to watch for include feeling agitated or confused, a fast heartbeat, sweating, shaking, muscle twitching or stiffness, and fever. This is uncommon, and the concern here is mostly based on how these drugs work rather than lots of reported cases. Please keep taking both exactly as prescribed, and let your doctor or pharmacist know if any of those symptoms show up. Your care team can watch for this and manage it.
Effect: Additive serotonergic activity from amitriptyline (a TCA with serotonin reuptake inhibition) plus levomilnacipran (an SNRI) increases the risk of serotonin syndrome.
- Mechanism: Pharmacodynamic (additive), not a PK/enzyme interaction. Neither agent is dependent on the other for activation.
- Direction: Increased serotonergic effect.
- Evidence: Theoretical; severity rated major.
- Onset: Unspecified; can occur after initiation or dose increase.
- Management: Use with extreme caution. Monitor for autonomic instability, neuromuscular abnormalities (clonus, hyperreflexia, rigidity), and mental status changes. If serotonin syndrome develops, discontinue both agents and give supportive care.
What happens
An increased risk of serotonin syndrome
Interaction Deep Dive
As a serotonergic agent, levomilnacipran carries a heightened, potentially life-threatening risk of serotonin syndrome when combined with another drug that acts on the serotonergic neurotransmitter system, so such combinations demand extreme caution. Any patient receiving levomilnacipran alongside other serotonergic drugs should be watched for the onset of serotonin syndrome. Should serotonin syndrome occur, both drugs should be stopped and supportive symptomatic treatment begun. When there is a clinical justification for using levomilnacipran together with other serotonergic drugs, patients should be advised of the elevated serotonin syndrome risk and monitored for symptoms1.
Why it happens (mechanism)
Additive serotonergic effects
How to manage this interaction
Your care team may still use these two together when the benefit is worthwhile, but they will do so carefully.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may monitor you more closely, especially when either dose is started or increased.
- Know the warning signs: agitation, confusion, fast heartbeat, sweating, shivering, tremor, muscle twitching or stiffness, or fever.
- Get medical help promptly if several of these appear together.
- Ask your pharmacist or prescriber before adding any other medicine, supplement, or over-the-counter product that affects serotonin.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amitriptyline and Levomilnacipran together?
Combining amitriptyline and levomilnacipran can add up to raise serotonin and, rarely, trigger serotonin syndrome. Keep taking both as prescribed, watch for symptoms like agitation, rapid heartbeat, sweating, and muscle twitching, and contact your care team if they appear. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Levomilnacipran 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 Levomilnacipran interaction managed?
Your care team may still use these two together when the benefit is worthwhile, but they will do so carefully. Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may monitor you more closely, especially when either dose is started or increased. Know the warning signs: agitation, confusion, fast heartbeat, sweating, shivering, tremor, muscle twitching or stiffness,… 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 Levomilnacipran 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: FETZIMA(R) oral extended-release capsules, levomilnacipran oral extended-release capsules. AbbVie Inc (per FDA), North Chicago, IL, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Levomilnacipran
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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