Amitriptyline and Nefazodone: 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
Nefazodone
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 of these medicines raise serotonin, a brain chemical that affects mood. Amitriptyline (Elavil) is a tricyclic antidepressant, and nefazodone is also an antidepressant. When you take them together, the serotonin effect can add up. In rare cases, too much serotonin causes a reaction called serotonin syndrome. Warning signs include shivering, muscle twitches or stiffness, a racing heart, sweating, fever, feeling very agitated, or confusion.
Please don't stop either medicine on your own. This concern is mostly based on how the drugs work rather than lots of real-world reports, and your care team can manage it safely by watching how you feel. Let them know about any new symptoms.
Mechanism: additive serotonergic effect. Amitriptyline inhibits serotonin (and norepinephrine) reuptake; nefazodone inhibits serotonin/norepinephrine reuptake and blocks 5-HT2 receptors. Neither is a prodrug here, so this is a pharmacodynamic, not PK, interaction that increases net serotonergic tone.
- Effect: increased risk of serotonin syndrome (autonomic instability, neuromuscular abnormalities, altered mental status).
- Severity/evidence: major but theoretical; onset unspecified.
- Management: use with caution; if coadministered, monitor for hyperreflexia, clonus, tremor, rigidity, hyperthermia, tachycardia, diaphoresis, agitation. Note nefazodone is also a strong CYP3A4 inhibitor. If serotonin syndrome develops, discontinue offending agents and give supportive care.
What happens
Increased risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)
Interaction Deep Dive
Amitriptyline functions as a serotonin reuptake inhibitor2, while nefazodone acts as a serotonin and norepinephrine reuptake inhibitor 3, meaning both agents influence serotonergic neurotransmitter systems. Because of additive serotonergic activity and the resulting potential for a heightened risk of serotonin syndrome, caution is advised when these drugs are taken together 32. When amitriptyline and nefazodone are administered concurrently, it may be appropriate to monitor for the signs and symptoms of serotonin syndrome throughout the course of treatment. The manifestations of serotonin syndrome 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 necessary therapy should be given 1.
Why it happens (mechanism)
Additive serotonergic effect
How to manage this interaction
The good news: your care team can manage this combination by keeping a closer eye on you.
- Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your team may monitor you more closely for signs of serotonin syndrome, especially when starting or increasing a dose.
- Watch for shivering, muscle twitching or stiffness, fever, sweating, a fast heartbeat, agitation, or confusion, and report them promptly.
- Ask your pharmacist or prescriber whether an alternative is appropriate, and mention all other serotonergic medicines or supplements you take.
Seek urgent care if severe symptoms like high fever, stiffness, or confusion appear.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amitriptyline and Nefazodone together?
Taking amitriptyline and nefazodone together can add up their serotonin effects and, rarely, trigger serotonin syndrome, so keep taking both as prescribed but watch for symptoms like tremor, fever, or agitation and report them to your care team. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Nefazodone 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 Nefazodone interaction managed?
The good news: your care team can manage this combination by keeping a closer eye on you. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your team may monitor you more closely for signs of serotonin syndrome, especially when starting or increasing a dose. Watch for shivering, muscle twitching or stiffness, fever, sweating, a fast heartbeat, agitation,… 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 Nefazodone 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: nefazodone HCl oral tablets, nefazodone HCl oral tablets. Ranbaxy Pharmaceuticals Inc. (per DailyMed), Jacksonville, FL, 2008.
Keep reading about Amitriptyline
Keep reading about Nefazodone
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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