The short answer
Avoid L-tryptophan supplements with tranylcypromine. Parnate labeling explicitly contraindicates tryptophan because of serotonin-syndrome risk. A reported severe reaction involved tryptophan, tranylcypromine and clomipramine together, so it cannot show how much of the risk came from tryptophan alone.
What this answer covers
Oral supplemental L-tryptophan with oral tranylcypromine. The multiagent case includes clomipramine and is not treated as a clean two-agent experiment; normal dietary protein is a separate question.
- Supplement or preparation
- L-Tryptophan
- Medication ingredient
- tranylcypromine
This is a named interaction
Tryptophan is specifically listed in the tranylcypromine interaction table. The concern is excess serotonergic activity, not a requirement to separate the supplement by an ordinary meal interval.
Keep the case's other medicine in view
The published severe case involved clomipramine as well as tranylcypromine and tryptophan. The patient required hospital treatment and recovered. Removing clomipramine from the description would overstate the evidence for a two-agent effect.
Do not turn this into a protein-free diet
This article concerns a concentrated tryptophan supplement. It does not replace the specific food guidance for an MAOI or mean all protein foods must be avoided. Discuss supplement and dietary questions separately with your clinician.
Get help for a possible reaction
New confusion, fever, sweating, rigidity or jerking after serotonergic substances warrants urgent medical assessment. Do not test a spacing schedule or stop tranylcypromine without a prescriber-directed plan.
Evidence and practical considerations
Side effects & toxicity
Current labeling explicitly contraindicates tryptophan. A full-text multiagent case documents serotonin syndrome after added tranylcypromine and tryptophan in a patient also taking clomipramine; other reports describe hypomania.
- Exact scope
- Oral supplemental L-tryptophan with oral tranylcypromine. The multiagent case includes clomipramine and is not treated as a clean two-agent experiment; normal dietary protein is a separate question. with Oral tranylcypromine tablets; current sulfate-tablet labeling uses the named active ingredient.
- Medication form and route
- oral
What remains uncertain
- Concomitant clomipramine prevents attributing the case to tryptophan alone. Neither the case nor label supplies an exact-pair incidence or a safe co-use dose.
Factors that may matter: Exact supplement preparation and complete concomitant-medication list require assessment..
Read the supporting source summaries
Source 1: Current U.S. prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral tranylcypromine sulfate tablets.
The label contraindicates sympathomimetic supplements, hydroxytryptophan, tryptophan and SAM-e; it names St. John's wort in the serotonin-syndrome warning and lists excessive caffeine among exposures to avoid.
How this applies: Primary authority for exact tranylcypromine tablet precautions. Named supplements and class-based applications are kept distinct.
A labeled contraindication is not a measurement of the frequency of an event with each product; L-tyrosine and Panax ginseng are not individually named.
Source 2: Human case report
pmc.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One 23-year-old man with bipolar disorder taking clomipramine and sodium valproate.
Altered mental status, jerking, fever, marked hypertension and elevated creatine kinase led to a serotonin-syndrome diagnosis. The patient improved with hospital treatment.
How this applies: Direct multiagent coexposure, not proof of a two-agent event rate.
Clomipramine is a major confounder; the separate contribution of tryptophan cannot be isolated. The narrative describes recovery despite imprecise fatality language elsewhere, which is not adopted.
Source 3: Human case reports
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Two patients receiving an MAOI; the abstract does not give per-patient medication and dose detail.
Hypomania followed addition of tryptophan.
How this applies: No original full text was available; indexing includes phenelzine and tranylcypromine but cannot be used to assign the exact regimen of each patient. Hypomania is not interchangeable with serotonin syndrome.
No original full text was available; indexing includes phenelzine and tranylcypromine but cannot be used to assign the exact regimen of each patient. Hypomania is not interchangeable with serotonin syndrome.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Initial targeted research draft. Inspected source material, adjudicated the current checker statements, and recorded preparation limits. Clinical review has not occurred. | |
| Research summary published |
Article revision: 927ce9509f8b6952
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.