Drug interactions
Fluvoxamine + L-tryptophan
Severity: Major
Fluvoxamine and L-tryptophan: major interaction.
Last updated Sources: Health Canada product monograph
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
L-tryptophan is the precursor of serotonin, and combining it with an SSRI can overstimulate serotonergic pathways. Cases of serotonin syndrome with agitation, tremor, hyperthermia and neuromuscular excitability have been described.
What this interaction means in plain words
Fluvoxamine and L-tryptophan 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.
Why it happens
Increased serotonin synthesis from tryptophan combined with reuptake inhibition by fluvoxamine causes additive serotonergic effects.
What to do
Avoid the combination where possible; if used, start with low tryptophan doses and monitor for signs of serotonin toxicity. Stop both agents and give supportive care 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 Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue Contraindicated
Frequently asked questions
Can I take Fluvoxamine with L-tryptophan?
MediHelp rates the interaction as major. Fluvoxamine and L-tryptophan 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. L-tryptophan is the precursor of serotonin, and combining it with an SSRI can overstimulate serotonergic pathways. Cases of serotonin syndrome with agitation, tremor, hyperthermia and neuromuscular excitability have been described.
How serious is the interaction between Fluvoxamine and L-tryptophan?
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 used, start with low tryptophan doses and monitor for signs of serotonin toxicity. Stop both agents and give supportive care if symptoms develop.
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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