Drug interactions
Diamorphine + Phenelzine
Severity: Major
Diamorphine and Phenelzine: 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 metabolized to morphine, and with MAOIs it may cause serotonin toxicity or exaggerated opioid effects including respiratory depression, hypotension and coma.
What this interaction means in plain words
Diamorphine and Phenelzine 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
Probable additive CNS depression and serotonergic effects; mechanism not firmly established.
What to do
Avoid within 14 days of MAOI therapy and use a non-opioid alternative where possible. If essential, use reduced, titrated doses with close monitoring of respiration, blood pressure and temperature.
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 Phenelzine
- 5-HTP + Phenelzine Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amoxapine + Phenelzine Contraindicated
- Atomoxetine + Phenelzine Contraindicated
- Benzphetamine + Phenelzine Contraindicated
- Brimonidine + Phenelzine Contraindicated
Frequently asked questions
Can I take Diamorphine with Phenelzine?
MediHelp rates the interaction as major. Diamorphine and Phenelzine 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 metabolized to morphine, and with MAOIs it may cause serotonin toxicity or exaggerated opioid effects including respiratory depression, hypotension and coma.
How serious is the interaction between Diamorphine and Phenelzine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid within 14 days of MAOI therapy and use a non-opioid alternative where possible. If essential, use reduced, titrated doses with close monitoring of respiration, blood pressure and temperature.
What other medicines interact with Phenelzine?
MediHelp also lists interactions of Phenelzine with, for example, 5-HTP, Amitriptyline, Amoxapine. The full list is on the Phenelzine page.
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