Drug interactions
Fenfluramine + Fluvoxamine
Severity: Major
Fenfluramine and Fluvoxamine: 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 increase serotonergic activity, so combining them may cause serotonin syndrome, with agitation, tremor, hyperthermia and neuromuscular excitation. Fluvoxamine can also inhibit CYP1A2 and CYP2D6, which contribute to fenfluramine clearance, and this may raise fenfluramine exposure.
What this interaction means in plain words
Fenfluramine and Fluvoxamine 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; Fluvoxamine belongs to Central Nervous System.
Why it happens
Additive serotonergic effects plus fluvoxamine inhibition of CYP1A2/CYP2D6 metabolism of fenfluramine.
What to do
Avoid the combination where possible; if it is necessary, monitor closely for serotonin syndrome and follow the labeled fenfluramine dose limits for strong CYP1A2 inhibitors.
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 Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue 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 Fluvoxamine?
MediHelp rates the interaction as major. Fenfluramine and Fluvoxamine 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 activity, so combining them may cause serotonin syndrome, with agitation, tremor, hyperthermia and neuromuscular excitation. Fluvoxamine can also inhibit CYP1A2 and CYP2D6, which contribute to fenfluramine clearance, and this may raise fenfluramine exposure.
How serious is the interaction between Fenfluramine and Fluvoxamine?
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 necessary, monitor closely for serotonin syndrome and follow the labeled fenfluramine dose limits for strong CYP1A2 inhibitors.
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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