Drug interactions
Fenfluramine + Fluoxetine
Severity: Major
Fenfluramine and Fluoxetine: major 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 enhance serotonergic activity, so combining them raises the risk of serotonin syndrome. In addition, fluoxetine inhibits CYP2D6 and CYP2C19 and may raise fenfluramine exposure. Features include agitation, tremor, hyperthermia and neuromuscular hyperactivity.
What this interaction means in plain words
Fenfluramine 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.
Fenfluramine belongs to Central Nervous System; Fluoxetine belongs to Central Nervous System.
Why it happens
Additive serotonergic effects (reuptake inhibition plus serotonin release) with possible CYP-mediated increases in fenfluramine levels.
What to do
Monitor for signs of serotonin syndrome, and stop one or both drugs if it occurs; adjust the fenfluramine dose as labeling directs.
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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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 Fenfluramine
- Fenfluramine + Isocarboxazid Contraindicated
- Fenfluramine + Linezolid Contraindicated
- Fenfluramine + Phenelzine Contraindicated
- Fenfluramine + Selegiline Contraindicated
- Fenfluramine + Tranylcypromine Contraindicated
- Almotriptan + Fenfluramine Major
Frequently asked questions
Can I take Fenfluramine with Fluoxetine?
MediHelp rates the interaction as major. Fenfluramine 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 activity, so combining them raises the risk of serotonin syndrome. In addition, fluoxetine inhibits CYP2D6 and CYP2C19 and may raise fenfluramine exposure. Features include agitation, tremor, hyperthermia and neuromuscular hyperactivity.
How serious is the interaction between Fenfluramine 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: Monitor for signs of serotonin syndrome, and stop one or both drugs if it occurs; adjust the fenfluramine dose as labeling directs.
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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