Drug interactions
Morphine + Phenelzine
Severity: Contraindicated
Morphine and Phenelzine: contraindicated interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Opioids given with non-selective MAO inhibitors such as phenelzine can lead to serotonin syndrome or to severe CNS depression, hypotension and hyperpyrexia. The reaction is best documented with meperidine, but labeling for morphine advises against use with MAOIs.
What this interaction means in plain words
Morphine and Phenelzine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Morphine belongs to Musculoskeletal; Phenelzine belongs to Central Nervous System.
Why it happens
MAO inhibition potentiates serotonergic and CNS depressant effects of the opioid through mechanisms not fully established for morphine.
What to do
Avoid morphine during MAOI therapy and for 14 days after stopping phenelzine; choose a non-opioid or alternative analgesic. If an opioid is unavoidable, use specialist supervision with close monitoring.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
- Alprazolam + Morphine Major
Other interactions of Phenelzine
- 5-HTP + Phenelzine Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amoxapine + Phenelzine Contraindicated
- Atomoxetine + Phenelzine Contraindicated
- Benzphetamine + Phenelzine Contraindicated
- Brimonidine + Phenelzine Contraindicated
Frequently asked questions
Can I take Morphine with Phenelzine?
MediHelp rates the interaction as contraindicated. Morphine and Phenelzine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Opioids given with non-selective MAO inhibitors such as phenelzine can lead to serotonin syndrome or to severe CNS depression, hypotension and hyperpyrexia. The reaction is best documented with meperidine, but labeling for morphine advises against use with MAOIs.
How serious is the interaction between Morphine and Phenelzine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid morphine during MAOI therapy and for 14 days after stopping phenelzine; choose a non-opioid or alternative analgesic. If an opioid is unavoidable, use specialist supervision with close monitoring.
What other medicines interact with Morphine?
MediHelp also lists interactions of Morphine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Morphine page.
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