Drug interactions
Metrizamide + Promethazine
Severity: Major
Metrizamide 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
Intrathecal contrast media such as metrizamide lower the seizure threshold, and phenothiazines like promethazine can add to this risk. Seizures after myelography are a serious complication.
What this interaction means in plain words
Metrizamide 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 lowering of the seizure threshold; the exact mechanism is not firmly established.
What to do
Avoid promethazine for at least 24 hours before and after intrathecal contrast administration, and use alternative antiemetics.
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
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Frequently asked questions
Can I take Metrizamide with Promethazine?
MediHelp rates the interaction as major. Metrizamide 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. Intrathecal contrast media such as metrizamide lower the seizure threshold, and phenothiazines like promethazine can add to this risk. Seizures after myelography are a serious complication.
How serious is the interaction between Metrizamide 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: Avoid promethazine for at least 24 hours before and after intrathecal contrast administration, and use alternative antiemetics.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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