Drug interactions
Diamorphine + Olanzapine
Severity: Major
Diamorphine and Olanzapine: major interaction.
Last updated Sources: UK SmPC
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
Diamorphine (heroin) is a potent opioid and combining it with olanzapine can cause deep sedation, hypotension and respiratory depression. Olanzapine also contributes anticholinergic effects such as constipation and urinary retention.
What this interaction means in plain words
Diamorphine and Olanzapine 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.
Why it happens
Additive CNS and respiratory depression from opioid and antipsychotic effects.
What to do
Use the lowest effective doses and monitor sedation, respiratory rate and blood pressure closely. Reduce doses in frail or opioid-naive patients.
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
- Olanzapine 10 mg orodispersible tablets - SmPC sections 4.3/4.5 (class statement: medicinal products that can cause central nervous system depression; "Caution should be exercised in patients who consume alcohol or receive medicinal products that can cause central nervous system depression.") — electronic medicines compendium (UK SmPC)
Other interactions of Olanzapine
Frequently asked questions
Can I take Diamorphine with Olanzapine?
MediHelp rates the interaction as major. Diamorphine and Olanzapine 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. Diamorphine (heroin) is a potent opioid and combining it with olanzapine can cause deep sedation, hypotension and respiratory depression. Olanzapine also contributes anticholinergic effects such as constipation and urinary retention.
How serious is the interaction between Diamorphine and Olanzapine?
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 the lowest effective doses and monitor sedation, respiratory rate and blood pressure closely. Reduce doses in frail or opioid-naive patients.
What other medicines interact with Olanzapine?
MediHelp also lists interactions of Olanzapine with, for example, Amisulpride, Amoxapine, Apomorphine. The full list is on the Olanzapine page.
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