Drug interactions
Morphine + Venlafaxine
Severity: Moderate
Morphine and Venlafaxine: moderate 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
Both drugs have serotonergic activity, so the combination carries a risk of serotonin syndrome, although it is uncommon. Venlafaxine is a weak CYP2D6 inhibitor and this has little effect on morphine, but additive sedation may occur.
What this interaction means in plain words
Morphine and Venlafaxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Morphine belongs to Musculoskeletal; Venlafaxine belongs to Central Nervous System.
Why it happens
Possible additive serotonergic effects; CYP2D6 inhibition is of minor relevance for morphine, which is cleared mainly by glucuronidation.
What to do
Monitor for serotonin syndrome features such as agitation, tremor, diarrhea, sweating and hyperthermia, especially after dose increases. Reduce doses or change therapy if symptoms appear.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
Other interactions of Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Frequently asked questions
Can I take Morphine with Venlafaxine?
MediHelp rates the interaction as moderate. Morphine and Venlafaxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both drugs have serotonergic activity, so the combination carries a risk of serotonin syndrome, although it is uncommon. Venlafaxine is a weak CYP2D6 inhibitor and this has little effect on morphine, but additive sedation may occur.
How serious is the interaction between Morphine and Venlafaxine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for serotonin syndrome features such as agitation, tremor, diarrhea, sweating and hyperthermia, especially after dose increases. Reduce doses or change therapy if symptoms appear.
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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