Drug interactions
Fluvoxamine + Guanfacine
Severity: Moderate
Fluvoxamine and Guanfacine: 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
Guanfacine is metabolized mainly by CYP3A4, and fluvoxamine as a moderate inhibitor can raise guanfacine levels. This may cause excess hypotension, bradycardia and sedation.
What this interaction means in plain words
Fluvoxamine and Guanfacine 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.
Fluvoxamine belongs to Central Nervous System; Guanfacine belongs to Cardiovascular.
Why it happens
Fluvoxamine inhibition of CYP3A4 reduces guanfacine clearance.
What to do
For extended-release guanfacine, reduce the dose to about half of the recommended dose when a strong or moderate CYP3A4 inhibitor is added. Monitor blood pressure and heart rate and watch for sedation.
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 Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue 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 Fluvoxamine with Guanfacine?
MediHelp rates the interaction as moderate. Fluvoxamine and Guanfacine 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 is metabolized mainly by CYP3A4, and fluvoxamine as a moderate inhibitor can raise guanfacine levels. This may cause excess hypotension, bradycardia and sedation.
How serious is the interaction between Fluvoxamine and Guanfacine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: For extended-release guanfacine, reduce the dose to about half of the recommended dose when a strong or moderate CYP3A4 inhibitor is added. Monitor blood pressure and heart rate and watch for sedation.
What other medicines interact with Fluvoxamine?
MediHelp also lists interactions of Fluvoxamine with, for example, Agomelatine, Alosetron, Fezolinetant. The full list is on the Fluvoxamine page.
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