Drug interactions
Fenfluramine + Mirtazapine
Severity: Major
Fenfluramine and Mirtazapine: 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
Fenfluramine releases serotonin and mirtazapine enhances serotonergic and noradrenergic neurotransmission, so combining them raises the risk of serotonin syndrome. Additive CNS effects such as somnolence may also occur.
What this interaction means in plain words
Fenfluramine and Mirtazapine 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; Mirtazapine belongs to Central Nervous System.
Why it happens
Additive serotonergic activity from fenfluramine-induced serotonin release and mirtazapine's effects on monoaminergic transmission.
What to do
Monitor for serotonin syndrome, including agitation, tremor, hyperthermia, diarrhea and clonus, particularly at initiation and dose changes. Stop one or both agents if symptoms develop.
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 Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline 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 Mirtazapine?
MediHelp rates the interaction as major. Fenfluramine and Mirtazapine 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 releases serotonin and mirtazapine enhances serotonergic and noradrenergic neurotransmission, so combining them raises the risk of serotonin syndrome. Additive CNS effects such as somnolence may also occur.
How serious is the interaction between Fenfluramine and Mirtazapine?
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 serotonin syndrome, including agitation, tremor, hyperthermia, diarrhea and clonus, particularly at initiation and dose changes. Stop one or both agents if symptoms develop.
What other medicines interact with Mirtazapine?
MediHelp also lists interactions of Mirtazapine with, for example, Isocarboxazid, Phenelzine, Pimozide. The full list is on the Mirtazapine page.
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