Drug interactions
Amitriptyline + Fenfluramine
Severity: Major
Amitriptyline and Fenfluramine: 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 affect serotonin and norepinephrine, so combined use may cause serotonergic toxicity. Fenfluramine is also a CYP2D6 substrate, and tricyclics may alter its effects.
What this interaction means in plain words
Amitriptyline and Fenfluramine 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.
Amitriptyline belongs to Central Nervous System; Fenfluramine belongs to Central Nervous System.
Why it happens
Additive serotonergic activity; fenfluramine releases serotonin while amitriptyline blocks its reuptake.
What to do
Monitor for agitation, tremor, hyperthermia and clonus, and reduce doses or stop one drug if serotonin syndrome is suspected. Review need for the combination regularly.
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 Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide 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 Amitriptyline with Fenfluramine?
MediHelp rates the interaction as major. Amitriptyline and Fenfluramine 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 affect serotonin and norepinephrine, so combined use may cause serotonergic toxicity. Fenfluramine is also a CYP2D6 substrate, and tricyclics may alter its effects.
How serious is the interaction between Amitriptyline and Fenfluramine?
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 agitation, tremor, hyperthermia and clonus, and reduce doses or stop one drug if serotonin syndrome is suspected. Review need for the combination regularly.
What other medicines interact with Amitriptyline?
MediHelp also lists interactions of Amitriptyline with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Amitriptyline page.
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