Drug interactions
Desvenlafaxine + Fenfluramine
Severity: Major
Desvenlafaxine and Fenfluramine: 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
Fenfluramine releases serotonin and, when combined with an SNRI, may raise the risk of serotonin syndrome. Symptoms include agitation, tremor, diarrhea, hyperthermia and clonus.
What this interaction means in plain words
Desvenlafaxine 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.
Desvenlafaxine belongs to Central Nervous System; Fenfluramine belongs to Central Nervous System.
Why it happens
Additive increase in synaptic serotonin from fenfluramine-induced release and SNRI reuptake inhibition.
What to do
Monitor for serotonin syndrome, particularly at initiation and dose changes. Stop one or both drugs 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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References
Other interactions of Desvenlafaxine
- Desvenlafaxine + Isocarboxazid Contraindicated
- Desvenlafaxine + Methylene blue Contraindicated
- Desvenlafaxine + Phenelzine Contraindicated
- Desvenlafaxine + Rasagiline Contraindicated
- Desvenlafaxine + Safinamide Contraindicated
- Desvenlafaxine + 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 Desvenlafaxine with Fenfluramine?
MediHelp rates the interaction as major. Desvenlafaxine 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. Fenfluramine releases serotonin and, when combined with an SNRI, may raise the risk of serotonin syndrome. Symptoms include agitation, tremor, diarrhea, hyperthermia and clonus.
How serious is the interaction between Desvenlafaxine 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 serotonin syndrome, particularly at initiation and dose changes. Stop one or both drugs if symptoms develop.
What other medicines interact with Desvenlafaxine?
MediHelp also lists interactions of Desvenlafaxine with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Desvenlafaxine page.
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