Drug interactions
Desvenlafaxine + Fluoxetine
Severity: Major
Desvenlafaxine and Fluoxetine: 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
Both drugs enhance serotonergic neurotransmission, so combined use increases the risk of serotonin syndrome. Fluoxetine may also modestly raise blood pressure effects of desvenlafaxine through added noradrenergic activity and CYP2D6 inhibition.
What this interaction means in plain words
Desvenlafaxine and Fluoxetine 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.
Desvenlafaxine belongs to Central Nervous System; Fluoxetine belongs to Central Nervous System.
Why it happens
Additive serotonin reuptake inhibition, with CYP2D6 inhibition by fluoxetine having a smaller effect on desvenlafaxine.
What to do
Avoid concurrent use of the two antidepressants unless specialist-supervised. Monitor for tremor, clonus, agitation, hyperthermia and diarrhea, and stop one agent if signs appear.
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 Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Other interactions of Desvenlafaxine
- Desvenlafaxine + Isocarboxazid Contraindicated
- Desvenlafaxine + Methylene blue Contraindicated
- Desvenlafaxine + Phenelzine Contraindicated
- Desvenlafaxine + Rasagiline Contraindicated
- Desvenlafaxine + Safinamide Contraindicated
- Desvenlafaxine + Selegiline Contraindicated
Frequently asked questions
Can I take Desvenlafaxine with Fluoxetine?
MediHelp rates the interaction as major. Desvenlafaxine and Fluoxetine 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. Both drugs enhance serotonergic neurotransmission, so combined use increases the risk of serotonin syndrome. Fluoxetine may also modestly raise blood pressure effects of desvenlafaxine through added noradrenergic activity and CYP2D6 inhibition.
How serious is the interaction between Desvenlafaxine and Fluoxetine?
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 concurrent use of the two antidepressants unless specialist-supervised. Monitor for tremor, clonus, agitation, hyperthermia and diarrhea, and stop one agent if signs appear.
What other medicines interact with Fluoxetine?
MediHelp also lists interactions of Fluoxetine with, for example, Isocarboxazid, Mavacamten, Methylene blue. The full list is on the Fluoxetine page.
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