Buprenorphine and Hyoscyamine: 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
Buprenorphine
Hyoscyamine
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 can slow down your gut and bladder. Buprenorphine is an opioid pain medicine, and opioids are well known for causing constipation. Hyoscyamine is an anticholinergic that relaxes muscles in your belly and bladder, which can also slow things down. Taken together, these effects can add up.
In rare cases this could lead to severe constipation where the gut nearly stops moving (called paralytic ileus), or trouble emptying your bladder. This concern is mostly theoretical, so try not to worry. Your care team can manage it by watching you and adjusting things. Let them know if you have belly pain, bloating, no bowel movements, or trouble urinating.
Effect: Additive reduction in GI and urinary tract motility from combining buprenorphine (opioid) with hyoscyamine (anticholinergic), raising the risk of severe constipation, urinary retention, and potentially paralytic ileus.
- Mechanism: Pharmacodynamic additive effect; opioid-mediated decrease in gastric motility plus anticholinergic smooth-muscle inhibition. Neither agent is a prodrug requiring activation.
- Direction: Enhanced constipating/anticholinergic effect (increased ADR risk).
- Evidence: Theoretical. Onset: unspecified. Severity: major.
- Management: Monitor for reduced bowel motility (distension, absent stools, abdominal pain) and urinary retention. Consider prophylactic bowel regimen; individualize dosing.
What happens
An increased risk of paralytic ileus
Interaction Deep Dive
When buprenorphine is taken together with an anticholinergic agent, the combination can lead to urinary retention or severe constipation that progresses to paralytic ileus. In patients receiving buprenorphine alongside anticholinergic drugs, watch for indications of urinary retention or diminished gastric motility1.
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. Here is how a care team typically handles this:
- Closer monitoring for constipation and urinary retention, especially early on.
- Individualized dosing that your team may adjust based on how you respond.
- Supportive steps like staying hydrated and, if needed, a bowel regimen your prescriber may recommend.
Call your pharmacist or doctor promptly if you have belly pain or bloating, no bowel movement for several days, or difficulty urinating. Seek urgent care if your abdomen becomes swollen and painful with vomiting, since this can signal a blocked gut.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Buprenorphine and Hyoscyamine together?
Buprenorphine and hyoscyamine can both slow the gut and bladder, so together they raise the risk of severe constipation or urinary retention. This is a theoretical but serious concern that your care team can manage with monitoring; report any belly pain, no bowel movements, or trouble urinating. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Hyoscyamine 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 Buprenorphine and Hyoscyamine interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. Here is how a care team typically handles this: Closer monitoring for constipation and urinary retention, especially early on. Individualized dosing that your team may adjust based on how you respond. Supportive steps like staying hydrated and, if needed, a bowel regimen your prescriber may recommend. Call your ph… 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 Buprenorphine or Hyoscyamine 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 (1)
- Product Information: BRIXADI(TM) subcutaneous extended-release injection, buprenorphine subcutaneous extended-release injection. Braeburn Inc (per FDA), Plymouth Meeting, PA, 2023. DailyMed
Keep reading about Buprenorphine
Keep reading about Hyoscyamine
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