Drug interactions
Belladonna and opium + Promethazine
Severity: Major
Belladonna and opium and Promethazine: 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
The opium component adds opioid sedation and respiratory depression to promethazine's sedative effect, while the belladonna component adds anticholinergic burden. Together they may cause marked drowsiness, constipation, urinary retention and respiratory depression.
What this interaction means in plain words
Belladonna and opium and Promethazine 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 plus additive antimuscarinic effects.
What to do
Use the lowest effective doses and monitor sedation and respiratory rate. Avoid concurrent alcohol and 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 Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Belladonna and opium with Promethazine?
MediHelp rates the interaction as major. Belladonna and opium and Promethazine 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. The opium component adds opioid sedation and respiratory depression to promethazine's sedative effect, while the belladonna component adds anticholinergic burden. Together they may cause marked drowsiness, constipation, urinary retention and respiratory depression.
How serious is the interaction between Belladonna and opium and Promethazine?
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 and respiratory rate. Avoid concurrent alcohol and other sedatives.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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