Supplement·Interactions·Reviewed June 9, 2026
L-Tryptophan interactions.
L-Tryptophan has 34 documented interactions in the NutriStack database: 25 to avoid or watch closely, 8 that need timing or caution, and 1 that work synergistically. The full list, with what each pairing does, is below.
L-Tryptophan at a glance.
A quick, data-grounded summary. The full table is below.
L-Tryptophan has 34 documented interactions in the NutriStack database: 25 to avoid or watch closely, 8 that need timing or caution, and 1 that work synergistically. The full list, with what each pairing does, is below.
Everything that interacts with l-tryptophan.
Every supplement and medication in the NutriStack database with a documented interaction with this substance, highest-severity first. Open any pair for the mechanism and sources.
| Substance | Interaction | What happens |
|---|---|---|
| 5-HTP | Contraindicated | Both 5-HTP and L-Tryptophan increase serotonin synthesis. Combining them creates additive serotonin excess, risking serotonin syndrome. details → |
| Citalopram | Contraindicated | L-Tryptophan is the upstream precursor to serotonin. Combined with citalopram's serotonin reuptake blockade, supplemental tryptophan can push... details → |
| Clomipramine | Contraindicated | Supplemental L-Tryptophan can increase serotonin production during clomipramine therapy. |
| Desvenlafaxine | Contraindicated | Desvenlafaxine is an SNRI with meaningful serotonin reuptake inhibition, and L-tryptophan is converted into serotonin. Supplemental L-tryptophan can... details → |
| Duloxetine | Contraindicated | Duloxetine blocks both serotonin and norepinephrine reuptake, and L-tryptophan provides extra substrate for serotonin synthesis. The combination can... details → |
| Fluvoxamine | Contraindicated | L-Tryptophan is the upstream precursor to serotonin; combined with fluvoxamine's serotonin reuptake blockade, it can drive synaptic serotonin to... details → |
| Isocarboxazid | Contraindicated | L-Tryptophan feeds serotonin synthesis while Isocarboxazid reduces serotonin breakdown, increasing risk of serotonin syndrome. details → |
| Levomilnacipran | Contraindicated | Supplemental L-Tryptophan increases serotonin precursor availability and may increase serotonin syndrome risk with levomilnacipran. |
| Linezolid | Contraindicated | L-Tryptophan can increase serotonergic tone and is unsafe with Linezolid's monoamine oxidase inhibitory activity. |
| MAOIs | Contraindicated | L-Tryptophan feeds serotonin synthesis while MAOIs reduce serotonin breakdown, increasing risk of serotonin syndrome. details → |
| MDMA | Contraindicated | L-Tryptophan combined with MDMA raises the risk of serotonin syndrome by supplying additional serotonin precursor on top of MDMA's... details → |
| Paroxetine | Contraindicated | L-Tryptophan is the upstream precursor to serotonin. Combined with paroxetine's potent serotonin reuptake blockade, supplemental L-tryptophan can... details → |
| Phenelzine | Contraindicated | L-Tryptophan feeds serotonin synthesis while Phenelzine reduces serotonin breakdown, increasing risk of serotonin syndrome. details → |
| Rasagiline | Contraindicated | L-Tryptophan supplementation increases serotonin precursor availability during MAO-B inhibitor therapy. |
| Selegiline | Contraindicated | L-Tryptophan feeds serotonin synthesis while Selegiline reduces serotonin breakdown, increasing risk of serotonin syndrome. details → |
| SSRIs/SNRIs/MAOIs | Contraindicated | L-Tryptophan is a serotonin precursor and can combine dangerously with serotonergic antidepressants or MAO inhibitors, increasing serotonin syndrome... details → |
| St. John's Wort | Contraindicated | St. John's Wort inhibits serotonin reuptake while L-Tryptophan increases serotonin synthesis. Risk of serotonin syndrome. |
| Tapentadol | Contraindicated | L-tryptophan can increase serotonin precursor availability and may raise serotonin syndrome risk with tapentadol. |
| Tramadol | Contraindicated | Tramadol has serotonergic activity in addition to its opioid effect, and L-Tryptophan is a serotonin precursor. Combining them can increase... details → |
| Tranylcypromine | Contraindicated | L-Tryptophan feeds serotonin synthesis while Tranylcypromine reduces serotonin breakdown, increasing risk of serotonin syndrome. details → |
| Trazodone | Contraindicated | L-Tryptophan is the upstream serotonin precursor. Trazodone is a serotonin reuptake inhibitor and 5-HT2A antagonist with active metabolite mCPP that... details → |
| Venlafaxine | Contraindicated | L-Tryptophan is the upstream dietary precursor for serotonin, and venlafaxine blocks serotonin reuptake. Concentrated tryptophan supplements can add... details → |
| Vilazodone | Contraindicated | L-Tryptophan supplements can increase serotonin synthesis and add to vilazodone's serotonergic effect. |
| Vortioxetine | Contraindicated | Supplemental L-Tryptophan can increase serotonin synthesis and raise serotonin-toxicity risk with vortioxetine. |
| L-Tyrosine | Conflict | Tyrosine and tryptophan compete with each other (and with other large neutral amino acids) for transport across the blood-brain barrier;... |
| Buspirone | Caution | L-Tryptophan is the dietary amino acid precursor for brain serotonin synthesis. Buspirone has serotonergic 5-HT1A activity, so concentrated... |
| Clonidine | Caution | L-Tryptophan, a serotonin precursor, has sedative and sleep-promoting effects that can add to the somnolence caused by clonidine. The combination... |
| Escitalopram | Caution | L-Tryptophan increases serotonin synthesis as its biosynthetic precursor. Combined with escitalopram's selective serotonin reuptake inhibition, the... details → |
| Fluoxetine | Caution | L-Tryptophan supplementation increases serotonin synthesis, and combined with fluoxetine's potent, long-lasting serotonin reuptake inhibition, can... details → |
| Isoniazid | Caution | Isoniazid is a weak, reversible inhibitor of monoamine oxidase. Combining it with high doses of L-tryptophan, a precursor to serotonin, can increase... |
| Sertraline | Caution | L-Tryptophan is the dietary amino acid precursor to serotonin. Supplemental tryptophan increases serotonin synthesis, and combined with sertraline's... details → |
| BCAAs | Timing Sensitive | This is the classic large neutral amino acid transporter competition described in the central fatigue hypothesis. BCAAs are sometimes used... details → |
| Essential Amino Acids | Timing Sensitive | EAA blends may already contain tryptophan; adding separate tryptophan can increase sedation or serotonergic exposure. |
| Vitamin B3 | Synergy | Tryptophan and niacin are linked through a single biosynthetic pathway. Supplemental tryptophan contributes to niacin/NAD+ status, and conversely,... |
The full l-tryptophan profile.
Benefits, dosing by goal, forms, and the cited evidence for this supplement.
Common l-tryptophan questions.
Quick answers drawn from the table above.
What interacts with L-Tryptophan?
In the NutriStack database, L-Tryptophan has 34 documented interactions with other supplements and medications. The most notable include 5-HTP, Citalopram, Clomipramine, Desvenlafaxine, and Duloxetine.
What should you not take with L-Tryptophan?
L-Tryptophan is flagged against 25 substances in the database, including 5-HTP, Citalopram, Clomipramine, Desvenlafaxine, Duloxetine, and Fluvoxamine. Review these with a clinician before combining, especially alongside prescription medications.
What works well with L-Tryptophan?
L-Tryptophan pairs synergistically with Vitamin B3 in the NutriStack database. Synergy still depends on dose and timing; open any pair for the detail.
Can you take L-Tryptophan with 5-HTP?
NutriStack classifies the L-Tryptophan and 5-HTP pairing as contraindicated: Both 5-HTP and L-Tryptophan increase serotonin synthesis. Combining them creates additive serotonin excess, risking serotonin syndrome. Do NOT combine. Choose one serotonin precursor, not both.
Check your whole stack
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