The short answer
Do not self-start L-5-HTP with nortriptyline. Official L-5-HTP guidance advises against combining it with antidepressants.
What this answer covers
Concentrated oral L-5-hydroxytryptophan, distinct from tryptophan and whole seed preparations.
- Supplement or preparation
- L-5-HTP
- Medication ingredient
- nortriptyline
The supplement warning is specific
Health Canada advises not to use L-5-HTP with antidepressants. Nortriptyline falls within that product precaution.
Keep precursor identities separate
L-5-HTP is not L-tryptophan. The nortriptyline label names tryptophan, while the separate L-5-HTP guidance supplies the relevant supplement warning.
Review before adding a mood supplement
Bring the actual ingredient amount and other serotonin-related products to the prescriber. No validated dose gap removes the stated concern.
Recognize concerning symptoms
Seek urgent medical care for a combination of agitation or confusion, fever or heavy sweating, tremor, muscle rigidity or repeated twitching. These can be signs of serotonin syndrome; a single nonspecific symptom does not establish the diagnosis.
Evidence and practical considerations
Side effects & toxicity
Conditional review follows the supplement’s explicit antidepressant precaution, not a demonstrated exact-pair event rate.
- Exact scope
- Concentrated oral L-5-hydroxytryptophan, distinct from tryptophan and whole seed preparations. with Exact oral nortriptyline hydrochloride capsules. RxNorm IN 7531/PIN 203130 hydrochloride. A nortriptyline measurement during amitriptyline use represents a metabolite exposure, not directly prescribed nortriptyline.
- Medication form and route
- oral
- Timing or duration
- Source-specific single-dose, repeated-dose and observational exposures distinguished.
What remains uncertain
- No exact-pair clinical toxicity study identified in the captured targeted results.
Factors that may matter: preparation and plant part; clinical indication; dose; other medicines; baseline alertness.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral nortriptyline.
Exact label names tryptophan and St John’s wort in serotonin-syndrome warnings; CYP2D6, cardiovascular and anticholinergic interactions require individual review.
How this applies: RxNorm IN 7531/PIN 203130 hydrochloride. A nortriptyline measurement during amitriptyline use represents a metabolite exposure, not directly prescribed nortriptyline.
No universal supplement interval, event rate or preparation equivalence established. Original label distinguishes warnings from measured pair-specific results.
Source 2: official product guidance
webprod.hc-sc.gc.ca · Source check Sep 10, 2026
Population: Adults considering oral L-5-HTP.
Advises not to use with antidepressants; gives serotonergic product precautions and drowsiness caution.
How this applies: The requested medicine is an antidepressant; this is a product-label precaution, not exact-pair clinical proof.
Does not quantify risk with each specific antidepressant or establish a safe supplement dose.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Current exact available claims adjudicated using original captures and explicit identity and comparator limits. | |
| Research summary published |
Article revision: 54d3bbef82d96dda
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.