Drug interactions
Diazepam + Perphenazine
Severity: Moderate
Diazepam and Perphenazine: 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
The combination can increase drowsiness, impaired psychomotor function and orthostatic hypotension. Respiratory depression is uncommon but possible at higher doses or in vulnerable patients.
What this interaction means in plain words
Diazepam and Perphenazine 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.
Diazepam belongs to Musculoskeletal; Perphenazine belongs to Central Nervous System.
Why it happens
Additive CNS depression from GABA-A potentiation and the sedative and alpha-blocking effects of the phenothiazine.
What to do
Use the lowest effective doses and monitor for sedation and orthostasis. Advise avoiding alcohol and other sedatives.
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 Diazepam
Other interactions of Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
Frequently asked questions
Can I take Diazepam with Perphenazine?
MediHelp rates the interaction as moderate. Diazepam and Perphenazine 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. The combination can increase drowsiness, impaired psychomotor function and orthostatic hypotension. Respiratory depression is uncommon but possible at higher doses or in vulnerable patients.
How serious is the interaction between Diazepam and Perphenazine?
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 and monitor for sedation and orthostasis. Advise avoiding alcohol and other sedatives.
What other medicines interact with Diazepam?
MediHelp also lists interactions of Diazepam with, for example, Calcium / magnesium / potassium / sodium oxybates, Alfentanil, Alprazolam. The full list is on the Diazepam page.
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