Selegiline and Morphine Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Selegiline
Morphine Injection
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.
What happens
Increased risk of the CNS and respiratory depressant effects of morphine and an increased risk of serotonin syndrome
Interaction Deep Dive
The concurrent administration of morphine and MAOIs is contraindicated1. Allow at least 14 days to elapse after discontinuing an MAOI before administering morphine. Concomitant administration of MAOIs with morphine may result in potentiation of the CNS and respiratory depressant effects of morphine. If concomitant use is required or morphine administration is necessary prior to 14 days after discontinuing an MAOI, monitor the patient closely for signs and symptoms of CNS or respiratory depression 4. However, it has been suggested that morphine is the narcotic analgesic of choice in patients receiving MAOIs and requiring emergency surgery 6. If urgent use of an opioid is necessary, use test doses and frequent titration of small doses of other opioids 2. Serotonin syndrome has also been reported with concomitant use 3.
Why it happens (mechanism)
Unknown; additive serotonergic effects
Literature reports
2 reports — tap to read
a) Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of opioids with serotonergic drugs 12.
b) In a case report, a 57-year-old woman that was well controlled on phenelzine for moderate depression presented to the hospital with signs and symptoms of serotonin syndrome. Ten days earlier, she was treated for cellulitis and received antiinfective agents, acetaminophen, and morphine sulfate oral solution. The patient was discharged after 7 days and then presented to the emergency department 3 days later with complaints of increasing visual hallucinations, restlessness, photophobia, dizziness, neck stiffness, occipital headache, sweating, and nausea for the last week. Morphine sulfate and phenelzine were stopped on admission and general supportive measures, including oxygen and fluids, were started. The patient was discharged 2 days later after full resolution of symptoms, and phenelzine was restarted on discharge without complications. The Drug Interaction Probability Scale (DIPS) indicated a probable relationship between phenelzine and morphine with a score of 6 3.
Common questions
Can I take Selegiline and Morphine Injection together?
Increased risk of the CNS and respiratory depressant effects of morphine and an increased risk of serotonin syndrome Always confirm with your pharmacist or prescriber before making any change.
How serious is the Selegiline and Morphine Injection interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Selegiline or Morphine Injection 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 (6)
- Product Information: DURAMORPH intravenous, epidural, intrathecal injection, morphine sulfate intravenous, epidural, intrathecal injection. Hikma Pharmaceuticals USA Inc (Per FDA), Berkeley, NJ, 2023. DailyMed
- Product Information: Morphine sulfate intravenous injection, morphine sulfate intravenous injection. Mallinckrodt Inc (Per FDA), St. Louis, MO, 2023. DailyMed
- Mateo-Carrasco H, Munoz-Aguilera EM, Garcia-Torrecillas JM, et al: Serotonin syndrome probably triggered by a morphine-phenelzine interaction. Pharmacotherapy 2015; 35(6):e102-e105. PubMed
- Product Information: KADIAN(R) oral extended-release capsules, morphine sulfate oral extended-release capsules. Actavis Kadian LLC (per FDA), Morristown, NJ, 2012. DailyMed
- Product Information: DepoDur(R) extended-release epidural injection, morphine sulfate extended-release epidural injection. EKR Therapeutics Inc, Bedminster, NJ, 2009. DailyMed
- Stack CG, Rogers P, & Linter SP: Monoamine oxidase inhibitors and anaesthesia. Br J Anaesth 1988; 60:222-227. DOI
Keep reading about Selegiline
Keep reading about Morphine Injection
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