Drug interactions
Clozapine + Morphine
Severity: Major
Clozapine and Morphine: major interaction.
Last updated Sources: US FDA label
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
Clozapine is strongly sedating and can cause hypotension and respiratory depression, which may be amplified by morphine. Cases of collapse and respiratory depression have been reported with clozapine plus CNS depressants.
What this interaction means in plain words
Clozapine and Morphine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Clozapine belongs to Central Nervous System; Morphine belongs to Musculoskeletal.
Why it happens
Additive CNS and respiratory depression, with additive orthostatic hypotension.
What to do
Use reduced opioid doses with slow titration and monitor sedation, blood pressure and respiratory rate, especially at initiation.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Morphine?
MediHelp rates the interaction as major. Clozapine and Morphine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Clozapine is strongly sedating and can cause hypotension and respiratory depression, which may be amplified by morphine. Cases of collapse and respiratory depression have been reported with clozapine plus CNS depressants.
How serious is the interaction between Clozapine and Morphine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use reduced opioid doses with slow titration and monitor sedation, blood pressure and respiratory rate, especially at initiation.
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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