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Dietary supplement

L-Tyrosine Ingredients & Drug Interactions

by NOW

L-Tyrosine label
See full label image
Powder 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 NOW 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 NOW

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

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HelloPharmacist Scorecard of L-Tyrosine 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.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 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 your body naturally makes and uses to produce neurotransmitters (brain chemicals) and thyroid hormones. There are no inactive ingredients listed.

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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: Neurotransmitter support and mental alertness.
  • We looked for evidence on: Cognitive function, Fatigue, Memory, Sleep deprivation, Stress, Athletic performance — and 4 related terms.
  • The strongest evidence on file: Tyrosine is rated "Possibly Effective" for Cognitive function (Natural Medicines).
  • Also on file: Tyrosine is rated "Possibly Effective" for Memory.
  • Also on file: Tyrosine is rated "Possibly Ineffective" for Athletic performance.

L-Tyrosine is effective for phenylketonuria (PKU), a rare genetic condition where the body can't process phenylalanine properly. It's possibly effective for cognitive function and memory support.

Evidence is insufficient to rate it for alcohol use disorder or dementia, and it appears possibly ineffective for athletic performance.

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 to your healthcare provider before regular use. The most common side effects in studies were fatigue, headache, heartburn, and nausea.

Larger doses can raise the risk of headache and fatigue; these often improve by lowering your dose. There isn't enough safety data to recommend supplemental doses unless a doctor advises it, and the same caution applies during breastfeeding.

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.

Check before starting if you take levodopa (Parkinson's medication) — tyrosine can reduce its absorption; space doses 2 hours apart. Also let us know if you're on thyroid hormones, as tyrosine may add to their effect.

These are Moderate-severity interactions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

L-Tyrosine is a straightforward single-ingredient supplement most useful if you have PKU or are exploring cognitive support. If you take levodopa or thyroid medications, check with us first — spacing or adjusting doses may be needed.

Talk to your pharmacist before starting regular use, especially if you're nursing.

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 Jun 20, 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

At a glance

General information

Key facts about L-Tyrosine, straight from the product label.

Brand NOW
Barcode (UPC) 733739002655
Net contents 4 Ounce(s); 113 Gram(s)
Market status On market
Date entered into DSLD Jun 20, 2024
DSLD ID 314456
Product type Amino Acid/protein
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Kosher, Halal, Gluten Free, Dairy 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 L-Tyrosine by NOW, 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:
350 mg
Maximum serving Sizes:
350 mg
Servings per container
323
UPC/BARCODE
733739002655
IngredientAmount% DV
L-Tyrosine350 mg--

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 Usage: Mix 1/4 level teaspoon in juice or water, preferably between meals, 1 to 3 times daily.

Formula

Tyrosine is a conditionally indispensable amino acid required for the production of the neurotransmitters dopamine, adrenaline, and noradrenaline, as well as for the skin pigment, melanin. Noradrenaline (norepinephrine) and adrenaline (epinephrine) are the main actors in the body’s response to acute stress and, along with dopamine, help to support a positive mood and mental alertness. In addition, tyrosine is especially critical for the normal function of the thyroid gland.

Pure Powder

Triangle K (Kosher)

NOW L-Tyrosine is Pharmaceutical Grade.

Crescent H (Halal)

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.

Precautions

Caution: For adults only.

Consult physician if pregnant/nursing, taking medication, or have a medical condition. Persons with thyroid disease (hyperthyroidism), melanoma, or those taking MAO inhibitors or other mood altering medications should seek the advice of a physician before consuming this product.

Keep out of reach of children.

Not manufactured with wheat, gluten, soy, corn, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

Formulation

Neurotransmitter Support Pharmaceutical Grade Healthy Glandular Function Supports Mental Alertness

Non-GMO

Not manufactured with wheat, gluten, soy, corn, milk, egg, fish, shellfish, tree nut or sesame ingredients.

Packaged and quality tested in the USA. Natural color variation may occur in this product.

FDA Statement of Identity

A Dietary Supplement

Seals/Symbols

Triangle K (Kosher)

GMP Quality Assured Crescent H (Halal)

General Statements

Amino Acids Family owned since 1968.

This bottle is made from 100% PCR (post-consumer recycled) resin.

Storage

This product is sold by weight not volume. Store in a cool, dry place after opening.

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

See for yourself

L-Tyrosine by NOW 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 NOW

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

Serving size350 mg Dosage formPowder Servings per container323 Amounts shown are per serving.

L-Tyrosine

Interacts with
21 drugs
350 mg per serving

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
Interaction report

L-Tyrosine by NOW 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.

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
Pharmacist Counseling Corner

L-Tyrosine by NOW: Common Questions

Does L-Tyrosine by NOW 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.
What is L-Tyrosine for?
It's an amino acid your body uses to make brain chemicals and thyroid hormones. It's proven effective for a rare genetic condition called PKU, and there's some evidence it may help with focus and memory.
What side effects might I notice?
Fatigue, headache, heartburn, and nausea are the most commonly reported. Larger doses make these more likely, but they usually get better if you lower your dose.
Is it safe if I'm breastfeeding?
There isn't enough safety data to know for sure. Talk to your doctor or pharmacist before taking this while nursing.
Why do I need to space it 2 hours from levodopa?
Tyrosine and levodopa both use the same transport system to get absorbed in your small intestine. Spacing them out keeps them from competing with each other, so your levodopa stays effective.
Does it have any fillers or additives?
No — there are no inactive ingredients listed for this powder.

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

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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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