Drug interactions
Dexfenfluramine + Fluoxetine
Severity: Major
Dexfenfluramine 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 increase serotonergic transmission, so combining them risks serotonin syndrome. Dexfenfluramine has been withdrawn from most markets, and fluoxetine may also raise its levels through CYP2D6 inhibition.
What this interaction means in plain words
Dexfenfluramine 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.
Why it happens
Additive serotonergic effects through reuptake inhibition and serotonin release, with CYP2D6 inhibition.
What to do
Avoid the combination where possible. If it cannot be avoided, monitor for agitation, tremor, hyperthermia and clonus and stop at the first signs.
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
Frequently asked questions
Can I take Dexfenfluramine with Fluoxetine?
MediHelp rates the interaction as major. Dexfenfluramine 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 increase serotonergic transmission, so combining them risks serotonin syndrome. Dexfenfluramine has been withdrawn from most markets, and fluoxetine may also raise its levels through CYP2D6 inhibition.
How serious is the interaction between Dexfenfluramine 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 the combination where possible. If it cannot be avoided, monitor for agitation, tremor, hyperthermia and clonus and stop at the first signs.
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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