Amitriptyline and Benzhydrocodone: 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
Benzhydrocodone
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.
Taking amitriptyline (Elavil) with benzhydrocodone can add up in two ways. First, both can affect a brain chemical called serotonin, and too much can rarely cause a reaction called serotonin syndrome (things like agitation, sweating, shaking, a fast heartbeat, or fever).
Second, both tend to slow down your gut and bladder. Together they can cause strong constipation or trouble emptying your bladder, and in rare cases the gut can nearly stop moving. This concern is based on how these drugs work rather than large studies. Please don't change anything on your own. Your care team can watch you closely and manage this safely.
Additive risk, theoretical evidence. Benzhydrocodone is a prodrug of hydrocodone; the concern involves the opioid, not activation issues. Two additive mechanisms:
- Serotonergic: amitriptyline (TCA with serotonergic activity) plus opioid raises risk of serotonin syndrome, especially at initiation or dose changes.
- Anticholinergic/GI: amitriptyline's anticholinergic effects plus opioid-induced reduced motility increase risk of urinary retention and severe constipation, potentially paralytic ileus.
Management: if co-prescribed, monitor closely for serotonin syndrome (autonomic instability, hyperreflexia, clonus, altered mentation) and for urinary retention/reduced gastric motility. Discontinue the opioid if serotonin syndrome is suspected. Doses may need individualization by the care team.
What happens
Increased risk of urinary retention and/or severe constipation leading to paralytic ileus and an increased risk of serotonin syndrome
Interaction Deep Dive
Serotonin syndrome has occurred when opioids such as benzhydrocodone or HYDROcodone (a prodrug of benzhydrocodone) are taken together with serotonergic agents. Furthermore, taking benzhydrocodone or HYDROcodone alongside anticholinergic agents may heighten the likelihood of urinary retention and severe constipation, potentially resulting in paralytic ileus. Should combined use be required, monitor the patient closely, especially when starting therapy and adjusting doses, for serotonin syndrome, and watch for indications of urinary retention or diminished gastric motility. If serotonin syndrome is suspected, stop benzhydrocodone or HYDROcodone1234.
Why it happens (mechanism)
Additive effects on gastric motility; additive serotonergic effects
How to manage this interaction
Your care team can manage this by watching you closely. Keep taking both medications exactly as prescribed unless your prescriber or pharmacist tells you otherwise.
- Watch for signs of serotonin syndrome: agitation, confusion, sweating, shivering, muscle twitching, fast heartbeat, or fever, especially when starting or changing a dose.
- Watch for trouble urinating or severe constipation (no bowel movement, bloating, belly pain).
- Report any of these to your care team promptly.
Your team may monitor you more closely and adjust doses as needed. If serotonin syndrome is suspected, the opioid would be stopped by your prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
Common questions
Can I take Amitriptyline and Benzhydrocodone together?
Amitriptyline and benzhydrocodone together can add up to raise the risk of serotonin syndrome, severe constipation, and urinary retention, so watch for these signs and keep in close contact with your care team. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Benzhydrocodone 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 Benzhydrocodone interaction managed?
Your care team can manage this by watching you closely. Keep taking both medications exactly as prescribed unless your prescriber or pharmacist tells you otherwise. Watch for signs of serotonin syndrome: agitation, confusion, sweating, shivering, muscle twitching, fast heartbeat, or fever, especially when starting or changing a dose. Watch for trouble urinating or severe constipation (no bowel mov… 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 Benzhydrocodone 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 (4)
- Product Information: NORCO 5/325 oral tablets, hydrocodone bitartrate acetaminophen oral tablets. Allergan USA, Inc. (per DailyMed), Irvine, CA, 2016.
- Product Information: VANTRELA(TM) ER oral extended-release tablets, hydrocodone bitartrate oral extended-release tablets. Teva Pharmaceuticals USA, Inc (per manufacturer), North Wales, PA, 2017. DailyMed
- Product Information: HYSINGLA(R) ER oral extended-release tablets, hydrocodone bitartrate oral extended-release tablets. Purdue Pharma LP (per FDA), Stamford, CT, 2023. DailyMed
- Product Information: APADAZ(R) oral tablets, benzhydrocodone acetaminophen oral tablets. Zevra Therapeutics, Inc. (per FDA), Celebration, FL, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Benzhydrocodone
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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