Drug interactions
Diamorphine + Diphenoxylate-atropine
Severity: Major
Diamorphine and Diphenoxylate-atropine: 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, so combining it with diphenoxylate adds to opioid effects, including sedation, respiratory depression and constipation. Atropine may further worsen constipation and urinary retention.
What this interaction means in plain words
Diamorphine and Diphenoxylate-atropine 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 mu-opioid receptor-mediated CNS and respiratory depression and reduced gut motility.
What to do
Avoid unnecessary co-use; if both are given, use the lowest doses and monitor sedation, respiratory rate and bowel function.
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 Diphenoxylate-atropine
- Diphenoxylate-atropine + Isocarboxazid Contraindicated
- Diphenoxylate-atropine + Phenelzine Contraindicated
- Diphenoxylate-atropine + Tranylcypromine Contraindicated
- Alfentanil + Diphenoxylate-atropine Major
- Alvimopan + Diphenoxylate-atropine Major
- Amitriptyline + Diphenoxylate-atropine Major
Frequently asked questions
Can I take Diamorphine with Diphenoxylate-atropine?
MediHelp rates the interaction as major. Diamorphine and Diphenoxylate-atropine 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, so combining it with diphenoxylate adds to opioid effects, including sedation, respiratory depression and constipation. Atropine may further worsen constipation and urinary retention.
How serious is the interaction between Diamorphine and Diphenoxylate-atropine?
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 unnecessary co-use; if both are given, use the lowest doses and monitor sedation, respiratory rate and bowel function.
What other medicines interact with Diphenoxylate-atropine?
MediHelp also lists interactions of Diphenoxylate-atropine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Diphenoxylate-atropine page.
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