L-Phenylalanine 500 mg Ingredients & Drug Interactions
by Solgar
What is this page for?
First and foremost: checking L-Phenylalanine 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-Phenylalanine 500 mg is a dietary supplement by Solgar with 1 active ingredient. Its ingredients are commonly taken for depression and mood, skin condition vitiligo, pain conditions.Based on those ingredients, 16 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are L-Phenylalanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Phenylalanine 500 mg by Solgar
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Phenylalanine 500 mg by Solgar — 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-Phenylalanine 500 mg by Solgar
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
This product contains one active ingredient: L-Phenylalanine, an amino acid (a building block of protein) at 500 mg per capsule. The capsule itself is made from vegetable cellulose, and it also contains vegetable magnesium stearate as an inactive binder.
Does it work?
Moderate evidence
The evidence on L-Phenylalanine is mixed. It's rated possibly effective for vitiligo (a skin condition causing loss of pigment).
For ADHD, the evidence suggests it may not help. For alcohol use disorder and multiple sclerosis, we don't have enough reliable data to know either way.
How safe is it?
Well-documented data
L-Phenylalanine is generally well tolerated at typical doses. The most common side effects reported are anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation.
If you have phenylketonuria (PKU), a rare genetic condition, you should not take this supplement because your body can't process phenylalanine safely. For pregnancy and breastfeeding, the safety data is mixed and incomplete — the facts show conflicting ratings.
Because supplement doses haven't been adequately studied in pregnancy or while breastfeeding, talk with your doctor or pharmacist about whether it's right for you in these situations.
Meds to double-check
Major interaction found
Before taking this product, check with your doctor or pharmacist if you take levodopa (Parkinson's drug), baclofen (muscle relaxer), or any monoamine oxidase inhibitor, or MAOI (certain older antidepressants and blood-pressure drugs). The levodopa interaction is the most serious — phenylalanine can reduce how well it works in your brain.
The bottom line
Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Major medication interactions have been identified, and safety information is well characterized.
This supplement is one to carefully check before starting, especially if you take levodopa for Parkinson's, baclofen for muscle spasticity, or any MAOI antidepressant or blood-pressure medication. If you have PKU, do not use it.
Talk with your doctor or pharmacist about your specific medications and whether this product is a fit for you.
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 Apr 23, 2020.
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-Phenylalanine 500 mg, straight from the product label.
| Brand | Solgar |
|---|---|
| Barcode (UPC) | 033984022010 |
| Net contents | 100 Vegetable Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Apr 23, 2020 |
| DSLD ID | 218596 |
| Product type | Amino Acid/protein |
| Supplement form | Capsule |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Vegetarian, Adult (18 - 50 Years), Kosher, Gluten Free, Dairy Free, Sugar 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-Phenylalanine 500 mg by Solgar, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Phenylalanine | 500 mg | -- |
Other ingredients: Vegetable Cellulose, Vegetable Magnesium Stearate
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.
Formula
L-Phenylalanine is an essential amino acid, one which is not synthesized by the body and must be obtained through diet or supplementation. L-Phenylalanine plays a key role in the biosynthesis of tyrosine, an amino acid required for the biosynthesis of the neurotransmitters dopamine and norepinephrine.
This formulation provides Free Form L-Phenylalanine to promote optimal absorption and assimilation.
Solgar’s KOF-K certification #K-1250
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.
Brand IP Statement(s)
2014 Solgar, Inc.
General Statements
Solgar since 1947
Formulation
Free form Pro-Neurotransmitter
Gluten, wheat & dairy free
Suitable for vegetarians
Free of: Gluten, wheat, dairy, soy, yeast, sugar, sodium, artificial flavor, sweetener, preservatives and color.
Seals/Symbols
K Parve (Kosher)
FDA Statement of Identity
Dietary Supplement
Suggested/Recommended/Usage/Directions
Suggested Use: As a dietary supplement for adults, take one (1) vegetable capsule twice daily, between meals or as directed by a healthcare practitioner.
Precautions
If you are pregnant, nursing, taking any medications or have a medical condition, please consult your healthcare practitioner before taking any dietary supplement.
Discontinue use and consult your healthcare practitioner if any adverse reactions occur.
Keep out of reach of children.
Do not use if outer bottle seal is missing or damaged.
Storage
Store at room temperature.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Phenylalanine 500 mg by Solgar 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-Phenylalanine 500 mg by Solgar
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Vegetarian Capsule(s) Dosage formCapsule Amounts shown are per serving.
L-Phenylalanine
Interacts with16 drugs
Phenylalanine is an essential amino acid the body uses to make brain chemicals like dopamine and norepinephrine. Some people take it for mood, vitilig...
L-Phenylalanine monograph & interactionsOther (inactive) ingredients: Vegetable Cellulose, Vegetable Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.
L-Phenylalanine 500 mg by Solgar Drug Interactions
HelloPharmacist Interaction Report
Solgar's L-Phenylalanine 500 mg interacts with several medication types, most seriously with levodopa (a Parkinson's drug).
L-Phenylalanine competes with levodopa for transport into the brain, which can reduce levodopa's levels there and worsen tremor, stiffness, and the on-off pattern that Parkinson's patients experience.
Read the full breakdown — every affected drug type, severity by severity
The supplement also has Moderate interactions with baclofen (a muscle relaxer) and monoamine oxidase inhibitors, or MAOIs (older antidepressants and blood-pressure drugs). With baclofen, phenylalanine can block its absorption in the gut and lower its effectiveness.
With non-selective MAOIs, there's a theoretical risk of a sudden dangerous spike in blood pressure (hypertensive crisis).
Altogether, these interactions span 16 individual medications. If you take any of these drug types, check your exact medications with the search tool on this page before starting this supplement.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Phenylalanine 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-Phenylalanine 500 mg interact with 16 drugs. Click any drug to see the details.
1 of the 1 ingredient in L-Phenylalanine 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Phenylalanine
Benserazide, LevodopaMadopar, Prolopa
How Benserazide, Levodopa interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineLevodopa Major
Interaction Summary
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Read the full L-phenylalanine + Benserazide, Levodopa interactionCarbidopa, LevodopaDhivy, Rytary, Sinemet, Sinemet CR
How Carbidopa, Levodopa interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineLevodopa Major
Interaction Summary
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Read the full L-phenylalanine + Carbidopa, Levodopa interactionCarbidopa, Levodopa, EntacaponeStalevo
How Carbidopa, Levodopa, Entacapone interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineLevodopa Major
Interaction Summary
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Read the full L-phenylalanine + Carbidopa, Levodopa, Entacapone interactionLevodopaInbrija, Larodopa
How Levodopa interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineLevodopa Major
Interaction Summary
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Read the full L-phenylalanine + Levodopa interactionLevodopa, CarbidopaDuodopa
How Levodopa, Carbidopa interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineLevodopa Major
Interaction Summary
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Read the full L-phenylalanine + Levodopa, Carbidopa interactionAmphetamineAdensys XR-ODT, Adzenys ER, Dyanavel XR, Mydayis
How Amphetamine interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Amphetamine interactionBaclofenFleqsuvy, Lioresal, Lyvispah, Ozobax
How Baclofen interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineBaclofen Moderate
Interaction Summary
Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.
Read the full L-phenylalanine + Baclofen interactionIsocarboxazidMarplan
How Isocarboxazid interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Isocarboxazid interactionLioresalLioresal Injection
How Lioresal interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineBaclofen Moderate
Interaction Summary
Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.
Read the full L-phenylalanine + Lioresal interactionMoclobemideManerix, Moclobemide
How Moclobemide interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Moclobemide interactionOzanimod HydrochlorideZeposia
How Ozanimod Hydrochloride interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Ozanimod Hydrochloride interactionPhenelzine SulfateNardil
How Phenelzine Sulfate interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Phenelzine Sulfate interactionRasagilineAzilect
How Rasagiline interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Rasagiline interactionSafinamide MesylateXadago
How Safinamide Mesylate interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Safinamide Mesylate interactionSelegilineCarbex, Eldepryl, Emsam, Zelapar
How Selegiline interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Selegiline interactionTranylcypromineParnate
How Tranylcypromine interacts with L-Phenylalanine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-phenylalanineMonoamine Oxidase Inhibitors (maois) Moderate
Interaction Summary
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
Read the full L-phenylalanine + Tranylcypromine interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Phenylalanine 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-Phenylalanine
Levodopa
Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.
Phenylalanine competes with levodopa for carrier-mediated transport into the brain. The resulting reduction in levels of levodopa in the brain can exacerbate tremor, rigidity, and the "on-off" phenomenon in patients with Parkinson disease.
Baclofen
Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.
Phenylalanine and baclofen share the same intestinal carrier for absorption; phenylalanine competitively inhibits the absorption of baclofen, reducing its plasma levels.
Monoamine Oxidase Inhibitors (Maois)
Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.
L-phenylalanine is metabolized to tyrosine. Some evidence suggests that L-phenylalanine, given with the non-selective MAOI pargyline, might prevent the elimination of tyramine, increasing the risk of hypertensive crisis. However, this was not reported in a small number of patients when using L-phenylalanine with the partially selective MAO-B inhibitor, selegiline.
Brand information
Manufacturer and brand details for L-Phenylalanine 500 mg, from the product label.
Solgar
See all Solgar products- Name
- Solgar, Inc.
- Street Address
- 500 Willow Tree Road
- City
- Leonia
- State
- NJ
- ZipCode
- 07605
- Phone Number
- 1-877-765-4274
- Web Address
- www.solgar.com
L-Phenylalanine 500 mg by Solgar: Common Questions
Does L-Phenylalanine 500 mg by Solgar interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Can I take this while pregnant or breastfeeding?
What are the most common side effects?
Does this work for ADHD?
Who should not take this supplement?
What is L-Phenylalanine used for?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Phenylalanine 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-Phenylalanine 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-Phenylalanine 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 23 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.
Phenylalanine 23 references
- Rouse B, Azen C, Koch R, et al. Maternal phenylketonuria collaborative Study (MPKUCS) offspring: facial anomalies, malformations, and early neurological sequelae. Am J Med Genet 1997;69:89-95. DOI
- Sturtevant FM. Use of aspartame in pregnancy. Int J Fertil 1985;30:85-7.
- Silkaitis RP, Mosnaim AD. Pathways linking L-phenylalanine and 2-phenylethylamine with p-tyramine in rabbit brain. Brain Res 1976;114:105-15.
- Lehmann WD, Theobald N, Fischer R, Heinrich HC. Stereospecificity of phenylalanine plasma kinetics and hydroxylation in man following oral application of a stable isotope-labelled pseudo-racemic mixture of L- and D-phenylalanine. Clin Chim Acta 1983;128 PubMed
- Mosnik DM, Spring B, Rogers K, Baruah S. Tardive dyskinesia exacerbated after ingestion of phenylalanine by schizophrenic patients. Neuropsychopharmacology 1997;16:136-46. PubMed
- Siddiqui AH, Stolk LM, Bhaggoe R, et al. L-phenylalanine and UVA irradiation in the treatment of vitiligo. Dermatology 1994;88:215-8. PubMed
- Birkmayer W, Riederer P, Linauer W, Knoll J. L-deprenyl plus L-phenylalanine in the treatment of depression. J Neural Transm 1984;59:81-7. PubMed
- Nutt JG, Woodward WR, Hammerstad JP, et al. The "on-off" phenomenon in Parkinson's disease. Relation to levodopa absorption and transport. N Engl J Med 1984;310:483-8. PubMed
- Baruzzi A, Contin M, Riva R, et al. Influence of meal ingestion time on pharmacokinetics of orally administered levodopa in parkinsonian patients. Clin Neuropharmacol 1987;10:527-37. PubMed
- Juncos JL, Fabbrini G, Mouradian MM, et al. Dietary influences on the antiparkinsonian response to levodopa. Arch Neurol 1987;44:1003-5. PubMed
- Eriksson T, Granerus AK, Linde A, et al. "On-off" phenomenon in Parkinson's disease: relationship between dopa and other large neutral amino acids in plasma. Neurology 1988;38:1245-8. PubMed
- Baker GB, Bornstein RA, Rouget AC, et al. Phenylethylaminergic mechanisms in attention-deficit disorder. Biol Psychiatry 1991;29:15-22.. PubMed
- Wood DR, Reimherr FW, Wender PH. Treatment of attention deficit disorder with DL-phenylalanine. Psychiatry Res 1985;16:21-6.. PubMed
- Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, DC: National Academy Press, 2002. Available at: http://www.n
- Cederbaum S. Phenylketonuria: an update. Curr Opin Pediatr 2002;14:702-6. PubMed
- Cejudo-Ferragud, E., Nacher, A., Polache, A., Cercos-Fortea, T., Merino, M., and Casabo, V. G. Evidence of competitive inhibition for the intestinal absorption of baclofen by phenylalanine. Int J of Pharm (Amsterdam) 1996;132:63-69. DOI
- Fischer, E., Heller, B., Nachon, M., and Spatz, H. Therapy of depression by phenylalanine. Preliminary note. Arzneimittelforschung. 1975;25(1):132.
- Beckmann, H., Strauss, M. A., and Ludolph, E. Dl-phenylalanine in depressed patients: an open study. J.Neural Transm. 1977;41(2-3):123-134. PubMed
- Sabelli, H. C., Fawcett, J., Gusovsky, F., Javaid, J. I., Wynn, P., Edwards, J., Jeffriess, H., and Kravitz, H. Clinical studies on the phenylethylamine hypothesis of affective disorder: urine and blood phenylacetic acid and phenylalanine dietary supplem
- Cotzias, G. C., Van Woert, M. H., and Schiffer, L. M. Aromatic amino acids and modification of parkinsonism. N Engl.J Med 2-16-1967;276(7):374-379. PubMed
- Kravitz, H. M., Sabelli, H. C., and Fawcett, J. Dietary supplements of phenylalanine and other amino acid precursors of brain neuroamines in the treatment of depressive disorders. J Am Osteopath.Assoc 1984;84(1 Suppl):119-123. DOI
- Mann, J., Peselow, E. D., Snyderman, S., and Gershon, S. D-phenylalanine in endogenous depression. Am.J.Psychiatry 1980;137(12):1611-1612. PubMed
- Katoulis AC, Alevizou A, Bozi E, et al. A randomized, double-blind, vehicle-controlled study of a preparation containing undecylenoyl phenylalanine 2% in the treatment of solar lentigines. Clin Exp Dermatol 2010;35(5):473-6. PubMed
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
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