Drug interactions
Fluvoxamine + Venlafaxine
Severity: Major
Fluvoxamine and Venlafaxine: major interaction.
Last updated Sources: US FDA label
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
Combining an SSRI with a serotonin-norepinephrine reuptake inhibitor increases the risk of serotonin syndrome. Fluvoxamine can also inhibit CYP2D6 and CYP2C19 to some extent, raising venlafaxine levels and adding to blood pressure and adverse-effect burden.
What this interaction means in plain words
Fluvoxamine and Venlafaxine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Fluvoxamine belongs to Central Nervous System; Venlafaxine belongs to Central Nervous System.
Why it happens
Additive serotonergic reuptake inhibition plus fluvoxamine-mediated inhibition of venlafaxine metabolism.
What to do
Avoid the combination where possible. If it is used deliberately, monitor for serotonin toxicity and blood pressure and use the lowest effective doses.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Frequently asked questions
Can I take Fluvoxamine with Venlafaxine?
MediHelp rates the interaction as major. Fluvoxamine and Venlafaxine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Combining an SSRI with a serotonin-norepinephrine reuptake inhibitor increases the risk of serotonin syndrome. Fluvoxamine can also inhibit CYP2D6 and CYP2C19 to some extent, raising venlafaxine levels and adding to blood pressure and adverse-effect burden.
How serious is the interaction between Fluvoxamine and Venlafaxine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible. If it is used deliberately, monitor for serotonin toxicity and blood pressure and use the lowest effective doses.
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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