Milnacipran 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
Milnacipran
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.
Amitriptyline (Elavil) and milnacipran (Savella) both raise levels of a brain chemical called serotonin. When you take them together, that serotonin activity can add up. In rare cases, too much serotonin can lead to a reaction called serotonin syndrome.
Signs to watch for include feeling agitated or confused, a fast heartbeat, sweating, shivering, muscle twitching or stiffness, fever, or diarrhea. This is uncommon, and the concern here is mostly based on how these drugs work rather than lots of reported cases. Keep taking both as prescribed, and let your doctor or pharmacist know if you notice these symptoms so your team can manage it.
Effect: Additive serotonergic activity increases the theoretical risk of serotonin syndrome. Amitriptyline (TCA with serotonin reuptake inhibition) plus milnacipran (SNRI) is a pharmacodynamic, not pharmacokinetic, interaction. Neither is a prodrug relevant here.
- Direction/magnitude: Additive serotonergic effect; magnitude not quantified.
- Onset: Unspecified; can occur early or after dose changes.
- Evidence: Theoretical, but severity rated major.
- Monitoring: Neuromuscular (clonus, hyperreflexia, rigidity, tremor), autonomic (tachycardia, labile BP, hyperthermia, diaphoresis), and mental status changes.
- Management: Concurrent use generally not recommended. If combined and clinically warranted, counsel patient and monitor. If serotonin syndrome occurs, discontinue offending agents and give supportive care.
What happens
An increased risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)
Interaction Deep Dive
Serotonergic neurotransmitter systems are influenced by both amitriptyline, which acts as a serotonin reuptake inhibitor2, and milnacipran, a selective inhibitor of serotonin and norepinephrine reuptake. Because these effects are additive and may raise the likelihood of serotonin syndrome, taking the two drugs together is not advised3. When amitriptyline and milnacipran are given concurrently, it may be appropriate to watch for the signs and symptoms of serotonin syndrome throughout therapy. Such symptoms encompass neuromuscular abnormalities (such as hyperreflexia, tremor, muscle rigidity, clonus, peripheral hypertonicity, and shivering), autonomic hyperactivity (such as tachycardia, mydriasis, diaphoresis, the presence of bowel sounds, and diarrhea), and alterations in mental status (such as agitation and delirium). This condition has the potential to be life-threatening. Should serotonin syndrome occur, the causative agents should be stopped and supportive care along with any other needed therapy should be given1.
Why it happens (mechanism)
Additive serotonergic effects
How to manage this interaction
Your care team can manage this combination if it is needed for your treatment.
- Keep taking both as prescribed unless your doctor tells you otherwise. Do not stop either drug on your own.
- Your team may monitor you more closely, especially when either dose is started or increased.
- Learn the warning signs of serotonin syndrome: agitation or confusion, fast heartbeat, high fever, heavy sweating, shivering, muscle twitching or stiffness, or diarrhea.
- Seek medical help right away if these symptoms appear. They can build quickly.
- Ask your pharmacist or prescriber before adding any new medication, including over-the-counter or herbal products, that may affect serotonin.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Milnacipran and Amitriptyline together?
Taking amitriptyline and milnacipran together adds up serotonin activity and can raise the risk of serotonin syndrome. Keep taking both as prescribed, know the warning signs, and get medical help right away if they appear. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Milnacipran 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 Milnacipran and Amitriptyline interaction managed?
Your care team can manage this combination if it is needed for your treatment. Keep taking both as prescribed unless your doctor tells you otherwise. Do not stop either drug on your own. Your team may monitor you more closely, especially when either dose is started or increased. Learn the warning signs of serotonin syndrome: agitation or confusion, fast heartbeat, high fever, heavy sweating, shive… 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 Milnacipran 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)
- Boyer EW & Shannon M: The serotonin syndrome. N Eng J Med 2005; 352(11):1112-1120. PubMed
- Product Information: amitriptyline HCl oral tablet, amitriptyline HCl oral tablet. RemedyRepack Inc. (per DailyMed), Indiana, PA, 2010. DailyMed
- Product Information: SAVELLA(R) oral tablets, milnacipran HCl oral tablets. Allergan USA Inc. (per FDA), Madison, NJ, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Milnacipran
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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