Benzphetamine 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
Benzphetamine
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.
Amitriptyline (Elavil) and benzphetamine both raise levels of a brain chemical called serotonin. When you take them together, that serotonin can build up too much, which can lead to a condition called serotonin syndrome.
Signs to watch for include feeling agitated or restless, a fast heartbeat, sweating, shaking, muscle twitching, or feeling too warm. This concern is mostly theoretical, meaning it hasn't been widely proven, but it's worth taking seriously. The good news is your care team can manage this. They may start with lower doses and keep a closer eye on you. Please talk with your pharmacist or doctor before making any changes.
Effect: Additive serotonergic activity increases the theoretical risk of serotonin syndrome. Amitriptyline inhibits serotonin (and norepinephrine) reuptake; benzphetamine, a sympathomimetic amine, enhances monoamine release. Neither is a prodrug relevant to this pharmacodynamic overlap.
- Mechanism: additive serotonergic (PD) effect; possible sustained CNS d-amphetamine concentrations and potentiated cardiovascular effects.
- Severity/onset: major; onset unspecified.
- Evidence: theoretical.
- Management: if coadministration is required, initiate at lower doses, monitor closely during initiation and titration (mental status, autonomic signs, neuromuscular signs, cardiovascular status). Discontinue both agents if serotonin syndrome is suspected.
What happens
An increased risk of serotonin syndrome
Interaction Deep Dive
When an amphetamine is given together with another serotonergic agent, serotonin syndrome may develop, since both agents act on the serotonergic neurotransmitter system12. There may also be prolonged elevations in brain d-amphetamine levels, and cardiovascular effects may be enhanced 1. Should the combined use of an amphetamine and such an agent be clinically necessary, begin with reduced doses and observe patients closely, particularly when starting therapy and when adjusting the dose. If serotonin syndrome is suspected, stop both medications 32.
Why it happens (mechanism)
Additive serotonergic effects
How to manage this interaction
Both drugs act on serotonin, so used together they can raise the risk of serotonin syndrome. This is a manageable situation, and your care team has clear ways to handle it.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may start at lower doses and adjust the dose in a way that is individualized for you.
- Expect closer monitoring, especially when starting or changing doses.
- Get help right away if you notice agitation, confusion, fast heartbeat, sweating, shaking, muscle stiffness or twitching, or a high fever.
Bring up any questions or new symptoms with your pharmacist or doctor.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Benzphetamine and Amitriptyline together?
Taking amitriptyline with benzphetamine can add up to raise the theoretical risk of serotonin syndrome. Keep taking both as prescribed, watch for symptoms like agitation, fast heartbeat, sweating or muscle twitching, and let your care team manage the dosing and monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Benzphetamine 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 Benzphetamine and Amitriptyline interaction managed?
Both drugs act on serotonin, so used together they can raise the risk of serotonin syndrome. This is a manageable situation, and your care team has clear ways to handle it. Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may start at lower doses and adjust the dose in a way that is individualized for you. Expect closer monitoring, especially when starting or ch… 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 Benzphetamine 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)
- Product Information: VYVANSE(R) oral capsules, oral chewable tablets, lisdexamfetamine dimesylate oral capsules, oral chewable tablets. Shire US Inc (per DailyMed), Lexington, MA, 2018. DailyMed
- Product Information: FETZIMA(R) oral extended-release capsules, levomilnacipran oral extended-release capsules. AbbVie Inc (per FDA), North Chicago, IL, 2023. DailyMed
- Product Information: ADDERALL(R) oral tablets, dextroamphetamine saccharate amphetamine aspartate dextroamphetamine sulfate amphetamine sulfate oral tablets. Teva Select Brands (per FDA), Horsham, PA, 2017. DailyMed
Keep reading about Amitriptyline
Keep reading about Benzphetamine
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