Drug interactions
Codeine + Duloxetine
Severity: Moderate
Codeine and Duloxetine: 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
Duloxetine is a moderate CYP2D6 inhibitor and may reduce activation of codeine to morphine, weakening analgesia. Both agents have serotonergic activity, so serotonin toxicity is also possible.
What this interaction means in plain words
Codeine and Duloxetine 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.
Codeine belongs to Musculoskeletal; Duloxetine belongs to Central Nervous System.
Why it happens
CYP2D6 inhibition reduces conversion of codeine to morphine; additive serotonergic effects.
What to do
Monitor pain control and consider an opioid not dependent on CYP2D6 activation if response is inadequate. Watch for signs of serotonin toxicity.
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 Codeine
- Alvimopan + Codeine Contraindicated
- Codeine + Isocarboxazid Contraindicated
- Codeine + Olanzapine / samidorphan Contraindicated
- Codeine + Phenelzine Contraindicated
- Codeine + Tranylcypromine Contraindicated
- Alfentanil + Codeine Major
Other interactions of Duloxetine
- Duloxetine + Isocarboxazid Contraindicated
- Duloxetine + Linezolid Contraindicated
- Duloxetine + Methylene blue Contraindicated
- Duloxetine + Phenelzine Contraindicated
- Duloxetine + Procarbazine Contraindicated
- Duloxetine + Rasagiline Contraindicated
Frequently asked questions
Can I take Codeine with Duloxetine?
MediHelp rates the interaction as moderate. Codeine and Duloxetine 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. Duloxetine is a moderate CYP2D6 inhibitor and may reduce activation of codeine to morphine, weakening analgesia. Both agents have serotonergic activity, so serotonin toxicity is also possible.
How serious is the interaction between Codeine and Duloxetine?
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 pain control and consider an opioid not dependent on CYP2D6 activation if response is inadequate. Watch for signs of serotonin toxicity.
What other medicines interact with Codeine?
MediHelp also lists interactions of Codeine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Codeine page.
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