Citalopram and L-Tryptophan: what the published research says
PubMed indexes 8 records that name Citalopram and L-Tryptophan together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.
Every statement below is attributed to a named, dated, linked source.
This page lists published research relevant to Citalopram and L-Tryptophan. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.
A study appearing here is not proof that an interaction exists. Two substances can be named together in a paper that never tested them in combination, and a source listed as background may cover only one of them.
Findings are quoted from each abstract as the authors wrote them. NutriStack has not re-analysed, pooled, or reconciled them, and they may disagree with each other.
NutriStack’s own interaction assessment for this pair is not published here. It has not completed qualified-human clinical review, so it is withheld from search. See the publication gate.
Nothing here is medical advice. Decisions about prescription medication and supplements belong with your prescriber or pharmacist, who can see your full regimen.
The research
8 studies naming Citalopram and L-Tryptophan.
Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.
“Our results support a decreased breakdown of TRP via KYN pathway and a failure to modulate TRP-KYN pathway during citalopram-induced acute stress together with an increased vascular sensitivity in migraine. These mechanisms may provide useful drug targets for future drug development.”
Names both Citalopram and L-Tryptophan in its title.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2013 · PMID 23303045
Randomized Controlled Trial
“Specifically, acute tryptophan depletion (ATD) produced a relatively larger NoGo response in the right IFG in subjects with low 5-HT2A BPP but reduced the NoGo response in those with high 5-HT2A BPP. These links between serotonergic function and response inhibition in healthy subjects may help to interpret serotonergic abnormalities underlying impulsivity in neuropsychiatric disorders.”
Names both Citalopram and L-Tryptophan in its title.
“Although TRP could be a useful strategy to improve the antidepressant effect of citalopram (Cervo et al. 2005), particularly in subjects with low 5-HT synthesis, the contribution of serotonergic and non-serotonergic mechanisms to TRP's effect remains to be elucidated.”
Names both Citalopram and L-Tryptophan in its title.
“There was a significant positive correlation in the baseline data between rated mood state and plasma cortisol and a significant inverse correlation between related mood state and plasma tryptophan concentration. Thus low mood appeared to be associated with low serotonin precursor availability as well as with high cortisol levels.”
Names both Citalopram and L-Tryptophan in its title.
“The results suggest that the plasma Trp and Tyr ratios may be determinants of clinical improvement in depressed patients to treatment with citalopram and maprotiline. However, further studies are needed on larger patient samples to allow a firm conclusion.”
Names both Citalopram and L-Tryptophan in its title.
Journal of child and adolescent psychopharmacology · 2013 · PMID 23510446
Human subjects
“This finding suggests that 5-HTTLPR and TPH2 genes may act in concert to modulate the clinical response to citalopram among children and adolescents with depression and/or anxiety disorders.”
Names both Citalopram and L-Tryptophan in its title.
“Our findings support the hypothesis that acute citalopram administration increases tryptophan (by inhibiting TDO activity) availability for 5-HT synthesis and activates serotonergic neurotransmission in limbic brain areas in rats exposed to FST paradigm. The mechanism of action of citalopram in ameliorating social stress related depressive disorder in humans is discussed.”
Names both Citalopram and L-Tryptophan in its title.
“The remission rate to citalopram treatment was worse in MDD subjects with the TPH1 A/A and A/C genotypes than in those with the TPH1 C/C genotype. Our results suggest that the A218C polymorphism of the TPH1 gene serves as a modulator of antidepressant activity, especially in terms of treatment remission.”
Names both Citalopram and L-Tryptophan in its title.
Limitations
What this evidence cannot tell you.
Search-based evidence indexes have real limits, and it is worth being explicit about them:
Selection. These records were found by searching PubMed titles and abstracts for both substance names alongside interaction and pharmacokinetic terms. Relevant work that phrases things differently, or is not indexed in PubMed, will be missing.
No effect size. The quoted conclusions are the authors’ words about their own study. We have not extracted effect direction or magnitude, and a single study’s conclusion is not a consensus.
Population mismatch. Findings in healthy volunteers, animals, or a specific patient group may not transfer to you, your dose, or your formulation.
Absence is not safety. Few published studies means the combination is under-studied, which is not the same as established as safe.
Nearby evidence
Other pairs with published research.
Pages covering Citalopram or L-Tryptophan alongside a different substance.
NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers Citalopram, L-Tryptophan, and several hundred other substances.
The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.
NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.