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Dietary supplement

L-Tyrosine Ingredients & Drug Interactions

by Douglas Laboratories

L-Tyrosine label
See full label image
Capsule Category: Amino Acid/protein
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Tyrosine 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: Moderate

L-Tyrosine is a dietary supplement by Douglas Laboratories with 1 active ingredient. Its ingredients are commonly taken for mental focus and alertness, coping with stress, fatigue and sleep loss.Based on those ingredients, 21 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Tyrosine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against L-Tyrosine by Douglas Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Tyrosine by Douglas Laboratories — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Tyrosine by Douglas Laboratories

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 Aug 13, 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: L-tyrosine, an amino acid (a building block of protein) that your body uses to make several important compounds, including thyroid hormones and brain chemicals. The capsule also contains inactive ingredients — gelatin, cellulose, water, magnesium stearate, and silica — which help deliver the amino acid.

Does it work?

Strong 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 Tyrosine's overall clinical evidence instead.

Strong

Strong clinical evidence supports Tyrosine 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: Phenylketonuria (PKU) — rated "Effective" (Natural Medicines).
  • On file: Cognitive function — rated "Possibly Effective" (Natural Medicines).
  • On file: Memory — rated "Possibly Effective" (Natural Medicines).

L-Tyrosine is established as effective for phenylketonuria (PKU), a genetic condition affecting how your body processes certain amino acids. It's possibly effective for supporting cognitive function and memory, though the evidence isn't conclusive.

For athletic performance, the current evidence suggests it's probably not effective, and there's not enough reliable evidence to rate it for alcohol use disorder or dementia.

The evidence, ingredient by ingredient Tyrosine

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.

L-Tyrosine is generally well tolerated in healthy adults, but talk with your doctor before starting regular use. Common side effects at typical doses include fatigue, headache, heartburn, and nausea.

Larger doses can trigger headache and fatigue more noticeably, and when combined with certain other supplements or medications, it may cause drowsiness, agitation, diarrhea, or vomiting — effects that may ease if you lower the dose. There isn't enough safety data during pregnancy, so avoid supplemental doses unless your doctor advises otherwise.

The same goes for breastfeeding — the data is too limited, so check with your doctor or pharmacist for personalized guidance.

Side effects, ingredient by ingredient Tyrosine

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Tyrosine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 21 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 you start, double-check with your doctor or pharmacist if you take levodopa (a Parkinson's medication) or any thyroid hormone replacement — both can have Moderate-level interactions with L-tyrosine. Spacing doses and timing matter, so this is worth a brief conversation with your pharmacist.

Check your own medication Run your meds through the checker above

The bottom line

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

L-Tyrosine is a well-studied amino acid that works for PKU and may help with memory and focus, though evidence for the latter is still developing. If you take levodopa for Parkinson's or thyroid hormone medications, you'll want to check with your doctor or pharmacist before starting this supplement.

For most other people in good health, it's generally well tolerated, but let your healthcare provider know you're considering it.

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 26, 2012.

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 L-Tyrosine, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 745287060506
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Apr 26, 2012
DSLD ID 8055
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
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 L-Tyrosine by Douglas Laboratories, 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:
1 Capsule(s)
Maximum serving Sizes:
4 Capsule(s)
Servings per container
100
UPC/BARCODE
745287060506
IngredientAmount% DV
L-Tyrosine800 mg--

Other ingredients: Gelatin, Cellulose, Water, Magnesium Stearate, Silica

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.
Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement, adults take 1 to 4 capsules daily between meals or as directed by physician.

It is recommended that this product be taken in conjunction with vitamins and minerals.

Precautions

Do not take with dairy products.

KEEP OUT OF REACH OF CHILDREN.

Tamper resistant package, do not use if outer seal is missing.

Storage

For optimal storage conditions, store in a cool, dry place. (59°-77°F/15°-25°C) (35-65% relative humidity)

General

TYR

FDA Statement of Identity

A Dietary Supplement

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

See for yourself

L-Tyrosine by Douglas Laboratories label

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

L-Tyrosine 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 L-Tyrosine by Douglas Laboratories

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

Serving size1 Capsule(s) Dosage formCapsule Servings per container100 Amounts shown are per serving.

L-Tyrosine

Interacts with
21 drugs
800 mg per serving Form: L-Tyrosine

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performan...

L-Tyrosine monograph & interactions

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

Interaction report

L-Tyrosine by Douglas Laboratories Drug Interactions

Want to check YOUR meds against L-Tyrosine?

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
21Drugs
21 Moderate

Ingredients driving the most interactions

L-Tyrosine 21

Individual Drug Interactions

The ingredients in L-Tyrosine interact with 21 drugs. Click any drug to see the details.

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

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Tyrosine 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-Tyrosine2 drug types · 21 drugs

Levodopa

Theoretically, tyrosine might decrease the effectiveness of levodopa.
Tyrosine and levodopa compete for absorption in the proximal duodenum by the large neutral amino acid (LNAA) transport system. Advise patients to separate doses of tyrosine and levodopa by at least 2 hours.

Likelihood Probable Evidence D
Thyroid Hormone

Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Tyrosine is a precursor to thyroxine and might increase levels of thyroid hormones.

Likelihood Probable Evidence D
L-Tyrosine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Tyrosine, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

L-Tyrosine by Douglas Laboratories: Common Questions

Does L-Tyrosine by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, L-Tyrosine has a known interaction with 21 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Tyrosine 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.
Does L-tyrosine really help with focus and memory?
The evidence suggests it possibly can, but it's not definitive. L-Tyrosine is possibly effective for cognitive function and memory based on current research, but we don't have the same level of proof we have for, say, treating PKU. It's worth trying if focus is what you're after, but don't expect dramatic results.
What are the most common side effects?
At standard doses, fatigue, headache, heartburn, and nausea are the most frequently reported. They're usually mild, but if they bother you, lowering your dose often helps.
Can I take this while pregnant or breastfeeding?
There isn't enough safety data to know either way — we simply don't have enough information. Talk with your doctor or pharmacist about whether it's right for you in these situations; they can weigh the specifics of your health.
Is L-tyrosine safe for athletes?
L-Tyrosine is probably not effective for athletic performance based on the evidence we have, so it may not give you the boost you're looking for in that area.
What exactly is L-tyrosine?
It's an amino acid — one of the building blocks your body uses to make proteins and important brain and thyroid chemicals. Your body can make some on its own, but you can also get it from food or supplements.

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

Not sure if L-Tyrosine 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.

L-Tyrosine label
Go deeper

The Full Monographs Behind L-Tyrosine’s Ingredients

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

Herb & supplement monograph

Tyrosine

Interacts with 21 drugs

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performance during short-term stress, sleep loss,...

Read the full Tyrosine monograph →
Sources

Sources & How We Checked

L-Tyrosine'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 4 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.

Tyrosine 4 references
  1. Meyer JS, Welch KM, Deshmukh VD, et al. Neurotransmitter precursor amino acids in the treatment of multi-infarct dementia and Alzheimer's disease. J Amer Geriat Soc 1977;25:289-98.
  2. DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
  3. Wood DR, Reimherr FW, Wender PH. Amino acid precursors for the treatment of attention deficit disorder, residual type. Psychopharmacol Bull 1985;21:146-9.
  4. van Spronsen FJ, van Rijn M, Bekhof J. Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets. Am J Clin Nutr 2001;73:153-7. PubMed

See these in context on the Tyrosine 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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