Drug interactions
Guanfacine + Perphenazine
Severity: Moderate
Guanfacine 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
Both drugs can lower blood pressure and cause sedation. Together they may cause additive hypotension, dizziness, syncope and drowsiness, particularly after dose increases.
What this interaction means in plain words
Guanfacine 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.
Guanfacine belongs to Cardiovascular; Perphenazine belongs to Central Nervous System.
Why it happens
Additive hypotensive effects: central alpha-2 agonism with guanfacine and alpha-1 adrenergic blockade with perphenazine, plus additive sedation.
What to do
Monitor blood pressure and heart rate, including orthostatic readings, when starting or adjusting either drug. Titrate slowly and warn patients about dizziness on standing.
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 Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
Other interactions of Guanfacine
- Clonidine + Guanfacine Major
- Guanfacine + Lofexidine Major
- Aldesleukin + Guanfacine Moderate
- Amiodarone + Guanfacine Moderate
- Amisulpride + Guanfacine Moderate
- Amitriptyline + Guanfacine Moderate
Frequently asked questions
Can I take Guanfacine with Perphenazine?
MediHelp rates the interaction as moderate. Guanfacine 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. Both drugs can lower blood pressure and cause sedation. Together they may cause additive hypotension, dizziness, syncope and drowsiness, particularly after dose increases.
How serious is the interaction between Guanfacine 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: Monitor blood pressure and heart rate, including orthostatic readings, when starting or adjusting either drug. Titrate slowly and warn patients about dizziness on standing.
What other medicines interact with Perphenazine?
MediHelp also lists interactions of Perphenazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Perphenazine page.
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