Drug interactions
Flurazepam + Promethazine
Severity: Moderate
Flurazepam and Promethazine: moderate 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
Promethazine increases the sedative effect of flurazepam, whose active metabolite is long-acting and accumulates, particularly in older adults. This raises the risk of next-day impairment, falls and respiratory depression.
What this interaction means in plain words
Flurazepam and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Additive CNS depression via H1 receptor blockade and GABA-A receptor potentiation.
What to do
Use the lowest effective doses, avoid in the elderly where possible, and monitor for residual sedation and impaired coordination.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Flurazepam with Promethazine?
MediHelp rates the interaction as moderate. Flurazepam and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Promethazine increases the sedative effect of flurazepam, whose active metabolite is long-acting and accumulates, particularly in older adults. This raises the risk of next-day impairment, falls and respiratory depression.
How serious is the interaction between Flurazepam and Promethazine?
MediHelp rates it moderate, 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, avoid in the elderly where possible, and monitor for residual sedation and impaired coordination.
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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