Drug interactions
Diamorphine + Dimenhydrinate
Severity: Major
Diamorphine and Dimenhydrinate: major 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
Dimenhydrinate adds to the sedative and respiratory depressant effects of diamorphine (heroin). It can also worsen constipation and urinary retention through anticholinergic action.
What this interaction means in plain words
Diamorphine and Dimenhydrinate 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 agonism plus H1-antihistamine sedation, with additive anticholinergic effects.
What to do
Use the lowest effective doses and monitor sedation level and respiratory rate. Avoid concurrent alcohol or other sedatives.
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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Other interactions of Dimenhydrinate
Frequently asked questions
Can I take Diamorphine with Dimenhydrinate?
MediHelp rates the interaction as major. Diamorphine and Dimenhydrinate 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. Dimenhydrinate adds to the sedative and respiratory depressant effects of diamorphine (heroin). It can also worsen constipation and urinary retention through anticholinergic action.
How serious is the interaction between Diamorphine and Dimenhydrinate?
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 level and respiratory rate. Avoid concurrent alcohol or other sedatives.
What other medicines interact with Dimenhydrinate?
MediHelp also lists interactions of Dimenhydrinate with, for example, Belladonna and opium, Brexanolone, Calcium / magnesium / potassium / sodium oxybates. The full list is on the Dimenhydrinate page.
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