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Dietary supplement

DL-Phenylalanine Ingredients & Drug Interactions

by DC

DL-Phenylalanine label
See full label image
Tablet Or Pill Category: Amino Acid/protein
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking DL-Phenylalanine 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

The interaction bottom line Most serious interaction: Major

DL-Phenylalanine is a dietary supplement by DC 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 Phenylalanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against DL-Phenylalanine by DC

Ask about any prescription or over-the-counter medication and we check it for interactions with DL-Phenylalanine by DC — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of DL-Phenylalanine by DC

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.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 23, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: phenylalanine, an amino acid your body uses to make proteins and neurotransmitters (chemical messengers in your brain). The inactive ingredients are vegetable cellulose, silica, and vegetable magnesium stearate — all common tablet binders and fillers.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Phenylalanine's overall clinical evidence instead.

Moderate

Some clinical evidence supports Phenylalanine for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Vitiligo — rated "Possibly Effective" (Natural Medicines).

Phenylalanine has possibly effective evidence for vitiligo (a skin condition causing loss of pigment). For ADHD, the evidence suggests it's possibly ineffective.

The evidence isn't established in the data we hold for alcohol use disorder or multiple sclerosis.

The evidence, ingredient by ingredient Phenylalanine

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Phenylalanine is generally well tolerated in typical doses. The most common side effects reported are anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation.

Do not take this supplement if you have PKU (phenylketonuria), a genetic condition that prevents you from metabolizing phenylalanine safely. The safety data advises against taking supplement doses during pregnancy or while breastfeeding, so talk with your doctor or pharmacist if you're in either situation.

Side effects, ingredient by ingredient Phenylalanine

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Phenylalanine.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 16 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before starting DL-Phenylalanine, check with your doctor or pharmacist if you take levodopa (Major severity), baclofen or MAOIs (Moderate severity). These are the main medication types where phenylalanine can interfere with how your drug works or raises safety concerns.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Major medication interactions have been identified, and safety information is well characterized.

This supplement may be worth considering if you're exploring options for vitiligo, but it isn't supported for ADHD. If you take levodopa, baclofen, or an MAOI antidepressant, check with your own doctor or pharmacist before adding it — the interaction with levodopa is a significant one.

The same goes if you have PKU or are pregnant or breastfeeding.

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 11, 2022.

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

At a glance

General information

Key facts about DL-Phenylalanine, straight from the product label.

Brand DC
Net contents 90 Tablet(s)
Market status On market
Date entered into DSLD Apr 11, 2022
DSLD ID 265716
Product type Amino Acid/protein
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other
Intended target group(s) Adult (18 - 50 Years), Women (not pregnant or lactating), Gluten Free, Dairy Free, Sugar Free
From the label
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 DL-Phenylalanine by DC, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
2 Tablet(s)
Maximum serving Sizes:
2 Tablet(s)
Servings per container
45
IngredientAmount% DV
Phenylalanine1000 mg--

Other ingredients: Vegetable Cellulose, Silica, Vegetable Magnesium Stearate

Tap any ingredient to jump to its full detail below.

Label statements
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

A racemic mixture consisting of equal parts of the D and L forms of Phenylalanine. Do not be misled by imitations or substitutions.

Mfg. in an FDA Registered Facility using Good Manufacturing Practices (GMPs)

Conforms to USP <2091> for weight. Meets USP <2040> disintegration for maximum bioavailability.

Contains no artificial color, flavor, sweetener, preservatives, sugar, starch, milk, lactose, soy, wheat, yeast, fish and is sodium free. Gluten free

Made in USA

Precautions

Tamper Evident: Do not use this product if imprinted foil seal under cap is broken or missing.

Keep out of reach of children.

Caution: If you are pregnant or nursing do not take this product.

Phenylketonurics: Contains phenylalanine.

Storage

Keep tightly closed. Store at room temperature: 59 degrees - 86 degrees F (15 degrees to 30 degrees C).

Formula

Phenylalanine is an essential amino acid.

General Statements

Was a capsule now a tablet

Brand IP Statement(s)

Quali Pure

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions: As a dietary supplement, take 2 tablets 15-30 minutes before morning and evening meals.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

DL-Phenylalanine by DC label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

DL-Phenylalanine label

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)
What’s inside

The Ingredients in DL-Phenylalanine by DC

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size2 Tablet(s) Dosage formTablet Or Pill Servings per container45 Amounts shown are per serving.

Phenylalanine

Interacts with
16 drugs
1000 mg per serving Form: DL-Phenylalanine

Phenylalanine is an essential amino acid the body uses to make brain chemicals like dopamine and norepinephrine. Some people take it for mood, vitilig...

Phenylalanine monograph & interactions

Other (inactive) ingredients: Vegetable Cellulose, Silica, Vegetable Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

DL-Phenylalanine by DC Drug Interactions

Want to check YOUR meds against DL-Phenylalanine?

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 checker
16Drugs
5 Major 11 Moderate

Ingredients driving the most interactions

Phenylalanine 16

Individual Drug Interactions

The ingredients in DL-Phenylalanine interact with 16 drugs. Click any drug to see the details.

1 of the 1 ingredient in DL-Phenylalanine interact with drugs. Each result below shows which ingredient is responsible. Phenylalanine

Each ingredient & the kinds of drugs it affects

For each ingredient in DL-Phenylalanine 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.

Phenylalanine3 drug types · 16 drugs

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.

Likelihood Probable Evidence B
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.

Likelihood Possible Evidence D
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.

Likelihood Possible Evidence D
Phenylalanine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for DL-Phenylalanine, from the product label.

DC

See all DC products
Name
Dee Cee Laboratories, Inc.
Street Address
304 Dee Cee Ct.
City
White House
State
TN
ZipCode
37188
Pharmacist Counseling Corner

DL-Phenylalanine by DC: Common Questions

Does DL-Phenylalanine by DC interact with any medications?
Yes. Based on its ingredients, DL-Phenylalanine has a known interaction with 16 medications, including 5 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
DL-Phenylalanine contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What are the most common side effects?
Anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation are the most commonly reported. The supplement is generally well tolerated in typical doses, but if any of these bother you, let your pharmacist know.
Can I take it while pregnant or breastfeeding?
The safety data advises against taking supplement doses of phenylalanine during pregnancy or while breastfeeding. Talk with your doctor or pharmacist for personalized advice — they can help you weigh the risks and benefits for your situation.
Who shouldn't take this product?
Anyone with PKU (phenylketonuria) must avoid it — your body can't break down phenylalanine safely. Also check with your doctor or pharmacist if you take levodopa, baclofen, or an MAOI, since this supplement can interfere with those medications.
What does phenylalanine actually do?
It's an amino acid your body uses to make proteins and chemical messengers in your brain. The evidence suggests it may help with vitiligo, but it isn't supported for ADHD.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Not sure if DL-Phenylalanine is safe with your meds?

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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.

DL-Phenylalanine label
Go deeper

The Full Monographs Behind DL-Phenylalanine’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Phenylalanine

Interacts with 16 drugs

Phenylalanine is an essential amino acid the body uses to make brain chemicals like dopamine and norepinephrine. Some people take it for mood, vitiligo, or pain, but the evidence is mostly l...

Read the full Phenylalanine monograph →
Sources

Sources & How We Checked

DL-Phenylalanine'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.

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
  1. 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
  2. Sturtevant FM. Use of aspartame in pregnancy. Int J Fertil 1985;30:85-7.
  3. Silkaitis RP, Mosnaim AD. Pathways linking L-phenylalanine and 2-phenylethylamine with p-tyramine in rabbit brain. Brain Res 1976;114:105-15.
  4. 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
  5. Mosnik DM, Spring B, Rogers K, Baruah S. Tardive dyskinesia exacerbated after ingestion of phenylalanine by schizophrenic patients. Neuropsychopharmacology 1997;16:136-46. PubMed
  6. Siddiqui AH, Stolk LM, Bhaggoe R, et al. L-phenylalanine and UVA irradiation in the treatment of vitiligo. Dermatology 1994;88:215-8. PubMed
  7. 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
  8. 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
  9. 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
  10. Juncos JL, Fabbrini G, Mouradian MM, et al. Dietary influences on the antiparkinsonian response to levodopa. Arch Neurol 1987;44:1003-5. PubMed
  11. 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
  12. Baker GB, Bornstein RA, Rouget AC, et al. Phenylethylaminergic mechanisms in attention-deficit disorder. Biol Psychiatry 1991;29:15-22.. PubMed
  13. Wood DR, Reimherr FW, Wender PH. Treatment of attention deficit disorder with DL-phenylalanine. Psychiatry Res 1985;16:21-6.. PubMed
  14. 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
  15. Cederbaum S. Phenylketonuria: an update. Curr Opin Pediatr 2002;14:702-6. PubMed
  16. 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
  17. Fischer, E., Heller, B., Nachon, M., and Spatz, H. Therapy of depression by phenylalanine. Preliminary note. Arzneimittelforschung. 1975;25(1):132.
  18. 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
  19. 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
  20. 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
  21. 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
  22. Mann, J., Peselow, E. D., Snyderman, S., and Gershon, S. D-phenylalanine in endogenous depression. Am.J.Psychiatry 1980;137(12):1611-1612. PubMed
  23. 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

See these in context on the Phenylalanine monograph →

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.

© 2021 Therapeutic Research Center, LLC

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