Belladonna and Buprenorphine: 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
Belladonna
No brand names on recordBuprenorphine
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. Belladonna is an anticholinergic, which naturally relaxes and slows the digestive tract. Buprenorphine is an opioid-type medicine that also slows things down and commonly causes constipation. Taken together, those effects can add up.
The main worry is that your bowel could slow so much that stool backs up, or you may have trouble emptying your bladder. In rare cases severe constipation can lead to a blocked gut (called paralytic ileus). This concern is theoretical, based on how the drugs work rather than lots of reports. The good news is your care team can watch for this and manage it easily.
Effect: Additive reduction in GI and urinary motility, with a theoretical increased risk of severe constipation, urinary retention, and paralytic ileus.
Mechanism: Pharmacodynamic additive effect. Belladonna alkaloids exert antimuscarinic (anticholinergic) slowing of gut motility; buprenorphine, a partial mu-opioid agonist, independently reduces GI motility and bladder emptying. Neither is a prodrug here; this is a PD, not PK, interaction.
- Direction: Additive, potentiated constipating/retentive effect.
- Evidence: Theoretical; magnitude unquantified.
- Onset: Unspecified.
- Management: Monitor for reduced bowel sounds, abdominal distension, constipation, and urinary retention. Consider bowel regimen; individualize dosing.
What happens
An increased risk of paralytic ileus
Interaction Deep Dive
When buprenorphine is given together with an anticholinergic agent, the combination can lead to urinary retention or severe constipation that progresses to paralytic ileus. Watch patients for indications of urinary retention or diminished gastric motility whenever buprenorphine is taken alongside anticholinergic medications1.
Why it happens (mechanism)
Additive effects on gastric motility
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Because the risk is mainly slowed digestion and bladder emptying, your care team will likely watch for warning signs.
- Watch for constipation, belly bloating or pain, no bowel movements, nausea/vomiting, or trouble urinating, and report these promptly.
- Your team may recommend a bowel regimen (fluids, fiber, or a stool softener) to keep things moving.
- Your doses may need to be adjusted and individualized by your care team, and they may monitor you more closely.
Ask your pharmacist or doctor before adding any other constipating or anticholinergic products.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Belladonna and Buprenorphine together?
Taking belladonna with buprenorphine can add up to worse constipation and possible trouble urinating, rarely leading to a blocked gut. Watch for these signs and tell your care team, who can adjust your plan and manage it. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Belladonna and Buprenorphine 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 Belladonna and Buprenorphine interaction managed?
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Because the risk is mainly slowed digestion and bladder emptying, your care team will likely watch for warning signs. Watch for constipation, belly bloating or pain, no bowel movements, nausea/vomiting, or trouble urinating, and report these promptly. Your team may recommend a bowel regimen (fluids, fiber,… 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 Belladonna or Buprenorphine 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 Belladonna
Keep reading about Buprenorphine
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