L-Tryptophan 500 mg Ingredients & Drug Interactions
by NOW
What is this page for?
First and foremost: checking L-Tryptophan 500 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.
Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy
L-Tryptophan 500 mg is a dietary supplement by NOW with 1 active ingredient. Its ingredients are commonly taken for sleep problems, low mood and depression, anxiety.Based on those ingredients, 394 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are L-Tryptophan. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Tryptophan 500 mg by NOW
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Tryptophan 500 mg by NOW — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of L-Tryptophan 500 mg by NOW
Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.
What’s inside
Full disclosure
L-Tryptophan 500 mg by NOW is a single-ingredient supplement: the amino acid L-tryptophan, which your body uses to make serotonin, a neurotransmitter tied to mood and sleep. The capsule also contains inactive ingredients—hypromellose, rice flour, ascorbyl palmitate, and stearic acid—which are fillers and binders.
Does it work?
Not established
The evidence for L-tryptophan's effectiveness is mixed and limited. For depression, the data rates it as possibly ineffective.
For anxiety, athletic performance, teeth grinding (bruxism), and premenstrual dysphoric disorder (PMDD), there isn't enough reliable evidence to rate whether it works. If you're considering it for a specific condition, talk it over with your doctor to weigh the evidence and explore other options.
How safe is it?
Well-documented data
L-Tryptophan is generally well tolerated when taken by mouth, but it can cause common side effects like belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting. A rare but serious concern: in 1989, over 1,500 cases of eosinophilia-myalgia syndrome (EMS)—a neurological disorder—were linked to contaminated L-tryptophan from a single Japanese manufacturer.
About 95% of those cases came from that tainted batch, and the FDA later restricted over-the-counter L-tryptophan imports. Modern products are made under different standards, but this history warrants caution.
During pregnancy, the safety data is inconsistent—some evidence suggests it may be unsafe, so it's best avoided. While breastfeeding, safety isn't established, so it should be avoided as well.
If you're pregnant or breastfeeding, talk with your doctor or pharmacist before taking this supplement.
Meds to double-check
Major interaction found
Before taking L-Tryptophan, double-check with your doctor or pharmacist if you use CNS depressants (benzodiazepines, sleep aids, narcotic painkillers, or other sedating drugs)—the combination could cause dangerous drowsiness. Also confirm your use of serotonergic drugs, such as antidepressants and migraine medications, because adding L-tryptophan might raise the risk of serotonin syndrome.
The bottom line
Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.
L-Tryptophan may be worth considering if you're interested in supporting serotonin naturally and you don't take CNS depressants or serotonergic drugs—but the evidence for depression and other conditions is weak or missing. If you take any brain-calming medication or antidepressant, you need to clear this with your doctor or pharmacist first.
Avoid it during pregnancy and breastfeeding unless your healthcare provider advises otherwise.
Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI
Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2024.
This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed
General information
Key facts about L-Tryptophan 500 mg, straight from the product label.
| Brand | NOW |
|---|---|
| Barcode (UPC) | 733739001665 |
| Net contents | 60 Veg Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Jul 25, 2024 |
| DSLD ID | 314454 |
| Product type | Amino Acid/protein |
| Supplement form | Capsule |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Vegan, Vegetarian, Adult (18 - 50 Years), Kosher, Halal, Gluten Free |
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.
Supplement Facts
The label details for L-Tryptophan 500 mg by NOW, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Tryptophan | 1000 mg | -- |
Other ingredients: Hypromellose, Rice Flour, Ascorbyl Palmitate, Stearic Acid
Tap any ingredient to jump to its full detail below.
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation
Supports Relaxation Encourages Positive Mood Promotes Restful Sleep
Non-GMO
Vegetarian/Vegan
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients.
Natural color variation may occur in this product.
Every lot of NOW L-Tryptophan is tested to be free of Peak E and microbial contamination.
Made and quality tested in the USA with globally sourced ingredients.
FDA Statement of Identity
A Dietary Supplement
General Statements
Amino Acids Family owned since 1968.
Precautions
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.
Caution: For adults only. Keep out of reach of children.
Consult physician if pregnant/nursing, taking medication (especially antidepressants such as SSRIs and MAOIs), or have a medical condition.
May cause drowsiness. Do not use with alcoholic beverages or while operating heavy machinery.
Storage
Store in a cool, dry place after opening.
Seals/Symbols
GMP Quality Assured Triangle K (Kosher) Crescent H (Halal)
Formula
Crescent H (Halal)
Triangle K (Kosher)
L-Tryptophan is an essential amino acid; therefore, it is not synthesized by the body and must be obtained from the diet. L-Tryptophan is critical for the production of serotonin and melatonin, which help to support a positive mood, healthy sleep patterns, and proper immune system function.
Suggested/Recommended/Usage/Directions
Suggested Usage: Take 1-2 capsules 2 to 3 times daily on an empty stomach, with final dose at bedtime, or as directed by your physician.
FDA Disclaimer Statement
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Tryptophan 500 mg by NOW label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.
View the full label (PDF)The Ingredients in L-Tryptophan 500 mg by NOW
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Veg Capsule(s) Dosage formCapsule Servings per container30 Amounts shown are per serving.
L-Tryptophan
Interacts with394 drugs
L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for...
L-Tryptophan monograph & interactionsOther (inactive) ingredients: Hypromellose, Rice Flour, Ascorbyl Palmitate, Stearic Acid. These complete the product’s ingredient list but are not active constituents.
L-Tryptophan 500 mg by NOW Drug Interactions
HelloPharmacist Interaction Report
L-Tryptophan 500 mg by NOW can interact with medications, chiefly through its effects on the brain's chemistry.
The most serious concern is with CNS depressants—drugs that slow brain activity, like benzodiazepines, sleep aids, and certain pain relievers. Combined use might cause excessive drowsiness and sedation because L-tryptophan itself can trigger fatigue and drowsiness.
Read the full breakdown — every affected drug type, severity by severity
L-Tryptophan also interacts with serotonergic drugs—antidepressants, migraine medications, and others that work on serotonin pathways. Because L-tryptophan is a building block for serotonin, pairing it with these drugs could amplify serotonin effects and theoretically raise the risk of serotonin syndrome (a potentially serious condition marked by agitation, confusion, rapid heart rate, and muscle rigidity) or blood vessel constriction in the brain.
Altogether, these interactions span 394 individual medications.
Before you start this supplement, check your complete medication list with your doctor or pharmacist—especially if you take any brain-calming drugs or antidepressants.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Tryptophan 500 mg?
Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.
Go to the checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in L-Tryptophan 500 mg interact with 394 drugs. Click any drug to see the details.
1 of the 1 ingredient in L-Tryptophan 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Tryptophan
Brompheniramine, Dextromethorphan, PhenylephrineDimetapp DM
How Brompheniramine, Dextromethorphan, Phenylephrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Brompheniramine, Dextromethorphan, Phenylephrine interactionBuproprion, DextromethorphanAuvelity
How Buproprion, Dextromethorphan interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Buproprion, Dextromethorphan interactionBuspironeBuSpar
How Buspirone interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Buspirone interactionCarbetapentane Tannate, Chlorpheniramine TannateTussi-12
How Carbetapentane Tannate, Chlorpheniramine Tannate interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Carbetapentane Tannate, Chlorpheniramine Tannate interactionCarbetapentane Tannate, Chlorpheniramine Tannate, Ephedrine Tannate, Phenylephrine TannateQuadratuss, Ry Tuss, Rynatuss, Tri Tannate Plus
How Carbetapentane Tannate, Chlorpheniramine Tannate, Ephedrine Tannate, Phenylephrine Tannate interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Carbetapentane Tannate, Chlorpheniramine Tannate, Ephedrine Tannate, Phenylephrine Tannate interactionCarbetapentane, Chlorpheniramine, PhenylephrineRicotuss
How Carbetapentane, Chlorpheniramine, Phenylephrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Carbetapentane, Chlorpheniramine, Phenylephrine interactionCarbetapentane, Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Potassium GuaiacolsulfonateCophene-X
How Carbetapentane, Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Potassium Guaiacolsulfonate interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Carbetapentane, Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Potassium Guaiacolsulfonate interactionChlorpheniramineChlor-Trimeton, Teldrin
How Chlorpheniramine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine interactionChlorpheniramine Maleate, Dextromethorphan HydrobromideCoricidin HBP Cough & Cold, Coricidin II Cough & Cold, Pediatric Vicks Formula 44m Cough & Cold Relief
How Chlorpheniramine Maleate, Dextromethorphan Hydrobromide interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine Maleate, Dextromethorphan Hydrobromide interactionChlorpheniramine Tannate, Phenylephrine TannateRicobid
How Chlorpheniramine Tannate, Phenylephrine Tannate interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine Tannate, Phenylephrine Tannate interactionChlorpheniramine Tannate, Phenylephrine Tannate, Pyrilamine TannateHistatan, R Tannamine, R-Tannate, Rhinatate, Tri Tannate, Triotann +1 more
How Chlorpheniramine Tannate, Phenylephrine Tannate, Pyrilamine Tannate interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine Tannate, Phenylephrine Tannate, Pyrilamine Tannate interactionChlorpheniramine, MethscopolamineAllerx
How Chlorpheniramine, Methscopolamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Methscopolamine interactionChlorpheniramine, Methscopolamine, PhenylephrineAH Chew, DA, DA II, Dallergy, Dallergy ER, Dura Vent DA +9 more
How Chlorpheniramine, Methscopolamine, Phenylephrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Methscopolamine, Phenylephrine interactionChlorpheniramine, Methscopolamine, PhenylpropanolaminePannaz
How Chlorpheniramine, Methscopolamine, Phenylpropanolamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Methscopolamine, Phenylpropanolamine interactionChlorpheniramine, Methscopolamine, PseudoephedrineMescolor, Rescon-Mx, Xiral
How Chlorpheniramine, Methscopolamine, Pseudoephedrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Methscopolamine, Pseudoephedrine interactionChlorpheniramine, Phenindamine, PhenylpropanolamineNolamine
How Chlorpheniramine, Phenindamine, Phenylpropanolamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenindamine, Phenylpropanolamine interactionChlorpheniramine, PhenylephrineDallergy JR, Ed A Hist, Histatab Plus, Rynatan
How Chlorpheniramine, Phenylephrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine interactionChlorpheniramine, Phenylephrine, PhenylpropanolamineRutuss
How Chlorpheniramine, Phenylephrine, Phenylpropanolamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine, Phenylpropanolamine interactionChlorpheniramine, Phenylephrine, Phenylpropanolamine, PhenyltoloxamineDe Con, Decongest, Naldecon, Nalspan SR, Tri Phen Mine Sr, Uni Decon +1 more
How Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Phenyltoloxamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Phenyltoloxamine interactionChlorpheniramine, Phenylephrine, Phenylpropanolamine, PyrilamineHistalet Forte, Poly Hist Forte, Vanex Forte
How Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine, Phenylpropanolamine, Pyrilamine interactionChlorpheniramine, Phenylephrine, PhenyltoloxamineCom Time, Comhist, Comhist LA, Linhist LA, Q Hist LA
How Chlorpheniramine, Phenylephrine, Phenyltoloxamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine, Phenyltoloxamine interactionChlorpheniramine, Phenylephrine, PyrilamineTanamine
How Chlorpheniramine, Phenylephrine, Pyrilamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylephrine, Pyrilamine interactionChlorpheniramine, PhenylpropanolamineAler-Releaf, Conex DA, Contac, Dehist, Histabid Duracaps, Ornade +1 more
How Chlorpheniramine, Phenylpropanolamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Phenylpropanolamine interactionChlorpheniramine, Pheylephrine, PyrilaminePhena-Plus
How Chlorpheniramine, Pheylephrine, Pyrilamine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Pheylephrine, Pyrilamine interactionChlorpheniramine, PseudoephedrineA.R.M., Anamine TD, Atrohist, Atrohist Ped, Brexin LA, Children's Deconamine +26 more
How Chlorpheniramine, Pseudoephedrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Pseudoephedrine interactionChlorpheniramine, Pyrilamine, PhenylephrineDuphrene
How Chlorpheniramine, Pyrilamine, Phenylephrine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Chlorpheniramine, Pyrilamine, Phenylephrine interactionCitalopramCelexa
How Citalopram interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Citalopram interactionClozapineClozaril, Versacloz
How Clozapine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Clozapine interactionCyclobenzaprineCyclobenzaprine, Cycloprine, Flexeril
How Cyclobenzaprine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Cyclobenzaprine interactionDesvenlafaxineKhedezla, Pristiq
How Desvenlafaxine interacts with L-Tryptophan 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tryptophanSerotonergic Drugs Moderate
Interaction Summary
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
Read the full L-tryptophan + Desvenlafaxine interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Tryptophan 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.
L-Tryptophan
Cns Depressants
Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.
Clinical research shows that L-tryptophan can cause fatigue and drowsiness.
Serotonergic Drugs
Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
L-tryptophan is a precursor to serotonin. Theoretically, combining serotonergic drugs with L-tryptophan might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.
Brand information
Manufacturer and brand details for L-Tryptophan 500 mg, from the product label.
NOW
See all NOW products- Name
- NOW Foods
- Street Address
- 395 S. Glen Ellyn Rd.
- City
- Bloomingdale
- State
- IL
- ZipCode
- 60108
- Web Address
- nowfoods.com
L-Tryptophan 500 mg by NOW: Common Questions
Does L-Tryptophan 500 mg by NOW interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
What is L-tryptophan, and what does it do in your body?
Can I take this if I'm on an antidepressant?
What are the most common side effects?
Is L-tryptophan safe to take while pregnant or breastfeeding?
Does L-tryptophan actually work for depression?
I remember hearing about L-tryptophan being unsafe years ago. Is it still safe to use?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Tryptophan 500 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.
The Full Monographs Behind L-Tryptophan 500 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
L-Tryptophan 500 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.
The 18 references behind this product’s interaction data
Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.
L-tryptophan 18 references
- Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. PubMed
- Devoe LD, Castillo RA, Searle NS. Maternal dietary substrates and human fetal biophysical activity. The effects of tryptophan and glucose on fetal breathing movements. Am J Obstet Gynecol 1986;155:135-9. DOI
- Lieberman HR, Corkin S, Spring BJ. The effects of dietary neurotransmitter precursors on human behavior. Am J Clin Nutr 1985;42:366-70. PubMed
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements. Information Paper on L-Tryptophan and 5-hydroxy-L-tryptophan, February 2001.
- Sullivan EA, Kamb ML, Jones JL, et al. The natural history of eosinophilia-myalgia syndrome in a tryptophan-exposed cohort in South Carolina. Arch Intern Med 1996;156:973-9. DOI
- Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. Am J Epidemiol 1993;138:154-9. PubMed
- Bohme A, Wolter M, Hoelzer D. L-tryptophan-related eosinophilia-myalgia syndrome possibly associated with a chronic B-lymphocytic leukemia. Ann Hematol 1998;77:235-8. PubMed
- Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
- Priori R, Conti F, Luan FL, et al. Chronic fatigue: a peculiar evolution of eosinophilia myalgia syndrome following treatment with L-tryptophan in four Italian adolescents. Eur J Pediatr 1994;153:344-6..
- Klein R, Berg PA. A comparative study on antibodies to nucleoli and 5-hydroxytryptamine in patients with fibromyalgia syndrome and tryptophan-induced eosinophilia-myalgia syndrome. Clin Investig 1994;72:541-9.. PubMed
- Simat TJ, Kleeberg KK, Muller B, Sierts A. Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan. Adv Exp Med Biol 1999;467:469-80.. PubMed
- Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;(1):CD003198. PubMed
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