Drug interactions
Dextromethorphan + Morphine
Severity: Minor
Dextromethorphan and Morphine: minor 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
Morphine has little serotonergic activity, so a serotonin syndrome risk is minimal. Additive sedation or respiratory depression is possible at high dextromethorphan doses.
What this interaction means in plain words
Dextromethorphan and Morphine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Dextromethorphan belongs to Respiratory; Morphine belongs to Musculoskeletal.
Why it happens
Mainly additive CNS depression; serotonergic interaction is weak and not well established.
What to do
No routine change is needed; monitor sedation and respiratory rate if dextromethorphan is used in large amounts.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Dextromethorphan
- Dextromethorphan + Isocarboxazid Contraindicated
- Dextromethorphan + Linezolid Contraindicated
- Dextromethorphan + Phenelzine Contraindicated
- Dextromethorphan + Rasagiline Contraindicated
- Dextromethorphan + Safinamide Contraindicated
- Dextromethorphan + Selegiline Contraindicated
Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
Frequently asked questions
Can I take Dextromethorphan with Morphine?
MediHelp rates the interaction as minor. Dextromethorphan and Morphine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Morphine has little serotonergic activity, so a serotonin syndrome risk is minimal. Additive sedation or respiratory depression is possible at high dextromethorphan doses.
How serious is the interaction between Dextromethorphan and Morphine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine change is needed; monitor sedation and respiratory rate if dextromethorphan is used in large amounts.
What other medicines interact with Dextromethorphan?
MediHelp also lists interactions of Dextromethorphan with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Dextromethorphan page.
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