Drug Interaction Report

Morphine Sulfate Liposome and Amitriptyline: Interaction Details

A pharmacist-reviewed analysis of the Morphine Sulfate Liposome and Amitriptyline interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

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

Elavil
+

Morphine Sulfate Liposome

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Jul 2, 2026
Editorial policy · Data sources
LinkedIn
Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 72 documented Morphine Sulfate Liposome interactions, 67 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
At a glance + Theoretical Effects may be stronger
The Bottom Line
Using amitriptyline with morphine can add up to cause constipation, urinary retention, and rarely serotonin syndrome, so watch for those symptoms and report them; keep taking both as prescribed unless your care team says otherwise.

You've been prescribed both amitriptyline (an older antidepressant) and morphine (a strong pain medicine). Taking them together can add up in two ways. First, both can slow down your gut and bladder, so you may have bad constipation, trouble urinating, or, rarely, your bowels can stop moving. Second, both can raise a brain chemical called serotonin, which in rare cases can cause serotonin syndrome (things like agitation, sweating, a racing heart, shakiness, or fever).

The good news: this is a known combination your care team can manage. Watch for those symptoms and tell them right away. Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise.

Additive pharmacodynamic interaction between amitriptyline (TCA, serotonergic and strongly anticholinergic) and liposomal morphine (opioid, mild serotonergic activity).

  • Direction: additive, increasing risk of anticholinergic and opioid GI/GU effects plus serotonin excess.
  • Effects: urinary retention, severe constipation, potential paralytic ileus; risk of serotonin syndrome.
  • Mechanism: additive reduction of gastric/bladder motility; additive serotonergic tone. Not a CYP prodrug issue.
  • Evidence: theoretical; severity major; onset unspecified.
  • Management: monitor closely at initiation and dose changes for serotonin syndrome and reduced GI/GU motility; discontinue morphine if serotonin syndrome is suspected. Consider bowel regimen.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

Increased risk of urinary retention, severe constipation, paralytic ileus and an increased risk of serotonin syndrome

Interaction Deep Dive

Serotonin syndrome has occurred when opioids like morphine are taken together with serotonergic agents. Furthermore, combining morphine with anticholinergic drugs may heighten the likelihood of urinary retention and severe constipation, potentially progressing to paralytic ileus. When such combined use cannot be avoided, monitor the patient closely for serotonin syndrome, especially at the start of therapy and when doses are being changed, and watch for indications of urinary retention or diminished gastric motility. Should serotonin syndrome be suspected, stop morphine1234567.

Why it happens (mechanism)

Additive effects on gastric motility; additive serotonergic effects

How to manage this interaction

This combination is used when needed, and your care team has clear ways to keep you safe.

  • Keep taking both as prescribed unless your doctor or pharmacist tells you to change something.
  • Your team will watch you more closely, especially when starting either drug or adjusting a dose. Doses may be adjusted and individualized by your care team.
  • Call your prescriber or pharmacist if you notice trouble urinating, severe constipation, no bowel movements with belly pain or bloating, or signs like agitation, sweating, shivering, fast heartbeat, muscle twitching, or fever.
  • Ask whether a stool softener or laxative plan makes sense for you.

Management is individual — confirm any change with your pharmacist or prescriber.

Literature reports

1 report — tap to read

a) Instances of serotonin syndrome, a condition that can be life-threatening, have been documented when opioids are taken together with serotonergic drugs 234.

Common questions

Can I take Morphine Sulfate Liposome and Amitriptyline together?

Using amitriptyline with morphine can add up to cause constipation, urinary retention, and rarely serotonin syndrome, so watch for those symptoms and report them; keep taking both as prescribed unless your care team says otherwise. Always confirm with your pharmacist or prescriber before making any change.

How serious is the Morphine Sulfate Liposome 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 Morphine Sulfate Liposome and Amitriptyline interaction managed?

This combination is used when needed, and your care team has clear ways to keep you safe. Keep taking both as prescribed unless your doctor or pharmacist tells you to change something. Your team will watch you more closely, especially when starting either drug or adjusting a dose. Doses may be adjusted and individualized by your care team. Call your prescriber or pharmacist if you notice trouble u… 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 Morphine Sulfate Liposome 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 (7)

  1. Product Information: KADIAN(R) oral extended-release capsules, morphine sulfate oral extended-release capsules. Allergan USA, Inc (per FDA), Madison, NJ, 2019. DailyMed
  2. Product Information: DURAMORPH intravenous, epidural, intrathecal injection, morphine sulfate intravenous, epidural, intrathecal injection. Hikma Pharmaceuticals USA Inc (Per FDA), Berkeley, NJ, 2023. DailyMed
  3. Product Information: MS CONTIN(R) oral extended-release tablets, morphine sulfate oral extended-release tablets. Purdue Pharma LP (per FDA), Stamford, CT, 2023. DailyMed
  4. Product Information: Morphine sulfate oral solution, morphine sulfate oral solution. Hikma Pharmaceuticals USA Inc (per FDA), Berkeley Heights, NJ, 2023. DailyMed
  5. Product Information: Morphine sulfate oral tablets, morphine sulfate oral tablets. Hikma Pharmaceuticals USA Inc.(Per FDA), Berkeley, NJ, 2023. DailyMed
  6. Product Information: INFUMORPH intrathecal, epidural injection, morphine sulfate intrathecal, epidural injection. Hikma Pharmaceuticals USA Inc (per FDA), Berkeley Heights, NJ, 2023. DailyMed
  7. Product Information: Morphine sulfate intravenous injection, morphine sulfate intravenous injection. Mallinckrodt Inc (Per FDA), St. Louis, MO, 2023. DailyMed
Was this write-up helpful?
Amitriptyline

Keep reading about Amitriptyline

All Amitriptyline interactions (525)
Also serious with: Safinamide Procarbazine Potassium Citrate Potassium Chloride
Morphine Sulfate Liposome

Keep reading about Morphine Sulfate Liposome

All Morphine Sulfate Liposome interactions (72)
Also serious with: Linezolid Injection Palonosetron Injection Naloxone Glycopyrronium Topical
Beyond drug–drug

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:

Amitriptyline + 1,4-butanediol Activated Charcoal American Hellebore Arsenic Beer Cesium Ephedra Gamma-hydroxybutyrate (ghb) + 288 more

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.

Coming soon

The instant two-drug checker is on its way.

In the meantime, browse the directory below to look up any drug and see its documented interactions.

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
This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.