Trospium / Xanomeline 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
Benzhydrocodone
No brand names on recordTrospium / Xanomeline
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.
Here's what's going on. Benzhydrocodone turns into hydrocodone in your body, which is an opioid pain medicine. Opioids naturally slow down your gut and can make it harder to empty your bladder. Cobenfy contains trospium, which is an anticholinergic that can also slow the gut and the bladder in the same way.
When you take both, those effects can add up. That means a higher chance of constipation or trouble urinating, and in rare cases the gut can slow so much it nearly stops (called an ileus). This is a theoretical concern based on how these drugs work, not from a lot of reports. The good news: your care team can watch for this and manage it easily.
Mechanism: Additive reduction in GI motility and urinary function. Benzhydrocodone is a prodrug hydrolyzed to hydrocodone (an opioid), which decreases gut motility and bladder emptying; trospium (in Cobenfy) is an anticholinergic (antimuscarinic) with the same net effect. Combined use is pharmacodynamically additive.
- Direction: Increased risk of urinary retention and/or severe constipation, potentially progressing to paralytic ileus.
- Evidence: Theoretical; onset unspecified.
- Severity: Major.
- Management: Monitor for reduced gastric motility (abdominal distension, absent bowel movements) and urinary retention. Consider prophylactic bowel regimen; dosing may be individualized and monitoring intensified by the care team.
What happens
Increased risk of urinary retention and/or severe constipation leading to paralytic ileus
Interaction Deep Dive
Taking HYDROcodone together with anticholinergics can heighten the likelihood of urinary retention and/or severe constipation, potentially progressing to paralytic ileus. When these anticholinergic agents are given alongside HYDROcodone, watch patients for indications of reduced gastric motility or urinary retention12.
Why it happens (mechanism)
Additive effects on gastric motility
How to manage this interaction
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical and manageable.
- Watch for constipation (no bowel movement for a few days), belly bloating or pain, or trouble urinating (can't go, weak stream, feeling of not emptying).
- Tell your pharmacist or doctor promptly if these happen, especially if you have severe cramping, vomiting, or a swollen belly.
- Ask your care team whether a stool softener or fiber plan makes sense for you.
- Your team may monitor you more closely and adjust things as needed for your situation.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Trospium / Xanomeline and Benzhydrocodone together?
Taking benzhydrocodone (an opioid) with trospium in Cobenfy can add up to cause constipation or trouble urinating, so watch for those and tell your care team if they occur. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Trospium / Xanomeline 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 Trospium / Xanomeline and Benzhydrocodone interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical and manageable. Watch for constipation (no bowel movement for a few days), belly bloating or pain, or trouble urinating (can't go, weak stream, feeling of not emptying). Tell your pharmacist or doctor promptly if these happen, especially if you have severe cramping, vomiting, or a swoll… 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.
Questions for your pharmacist
- Does my dose of Trospium / Xanomeline 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 (2)
- 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
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