Drug interactions
Guanfacine + Thioridazine
Severity: Moderate
Guanfacine and Thioridazine: 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, so combined use may cause hypotension, dizziness and syncope. Both are also sedating, which adds to the risk of falls and daytime somnolence.
What this interaction means in plain words
Guanfacine and Thioridazine 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; Thioridazine belongs to Central Nervous System.
Why it happens
Additive hypotensive and sedative effects (central alpha-2 agonism plus alpha-adrenergic blockade by thioridazine).
What to do
Monitor blood pressure and orthostatic symptoms when starting or adjusting either drug, and titrate doses gradually. Counsel patients about sedation and rising slowly.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
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 Thioridazine?
MediHelp rates the interaction as moderate. Guanfacine and Thioridazine 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, so combined use may cause hypotension, dizziness and syncope. Both are also sedating, which adds to the risk of falls and daytime somnolence.
How serious is the interaction between Guanfacine and Thioridazine?
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 orthostatic symptoms when starting or adjusting either drug, and titrate doses gradually. Counsel patients about sedation and rising slowly.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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