L-Tyrosine 500 mg Ingredients & Drug Interactions
by NOW
What is this page for?
First and foremost: checking L-Tyrosine 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-Tyrosine 500 mg 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.
Check Your Meds Against L-Tyrosine 500 mg by NOW
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Tyrosine 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-Tyrosine 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-Tyrosine 500 mg by NOW contains one active ingredient: L-tyrosine, an amino acid your body uses to make neurotransmitters (brain chemicals) and thyroid hormones. The capsule itself is filled with inactive ingredients — hypromellose, stearic acid, and silicon dioxide — which help hold the product together and have no active role.
Does it work?
Moderate evidence
L-Tyrosine is effective for phenylketonuria (PKU), a rare inherited metabolic condition. It is possibly effective for cognitive function and memory — meaning there's some evidence it may help, but more research is needed.
For athletic performance, the evidence suggests it probably doesn't work. There isn't enough reliable evidence to rate it for alcohol use disorder or dementia.
How safe is it?
Well-documented data
L-Tyrosine is generally well tolerated in healthy adults, but we'd recommend talking to a healthcare provider before you start taking it regularly. The most common side effects in trials were fatigue, headache, heartburn, and nausea.
There isn't enough safety data on L-tyrosine in pregnancy and lactation to know whether it's safe — talk with your doctor or pharmacist before taking it if you're pregnant, planning to become pregnant, or breastfeeding.
Meds to double-check
Moderate interaction found
Before taking L-Tyrosine 500 mg, make sure your doctor or pharmacist knows if you take levodopa (Moderate interaction — separation of doses may be needed) or any thyroid hormone medication (Moderate interaction — additive effects possible). These are the only medication types with documented interactions in our data.
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 500 mg is mainly supported for PKU and shows some promise for memory and focus, though the evidence isn't definitive. It works best for people who don't take levodopa or thyroid medications — if you do, check with your doctor or pharmacist first.
Side effects are usually mild and most people tolerate it well. Have a conversation with your own healthcare provider to see if it fits your needs.
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
General information
Key facts about L-Tyrosine 500 mg, straight from the product label.
| Brand | NOW |
|---|---|
| Barcode (UPC) | 733739001627 |
| Net contents | 120 Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Jun 20, 2024 |
| DSLD ID | 314457 |
| Product type | Amino Acid/protein |
| Supplement form | Capsule |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years), Kosher, Halal, Gluten Free, Dairy 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-Tyrosine 500 mg by NOW, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Tyrosine | 500 mg | -- |
Other ingredients: Hypromellose, Stearic Acid, Silicon Dioxide
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.
Suggested/Recommended/Usage/Directions
Suggested Usage: Take 1 capsule 1 to 3 times daily, preferably between meals.
Formula
L-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, L-Tyrosine is especially critical for the normal function of the thyroid gland.
Triangle K (Kosher)
The L-Tyrosine used in this product is Pharmaceutical Grade.
Crescent H (Halal)
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, 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, milk, egg, fish, shellfish, tree nut or sesame ingredients.
Made and quality tested in the USA with globally sourced ingredients. 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.
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.
Storage
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.
L-Tyrosine 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-Tyrosine 500 mg by NOW
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 container120 Amounts shown are per serving.
L-Tyrosine
Interacts with21 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 performan...
L-Tyrosine monograph & interactionsOther (inactive) ingredients: Hypromellose, Stearic Acid, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.
L-Tyrosine 500 mg by NOW Drug Interactions
HelloPharmacist Interaction Report
L-Tyrosine 500 mg by NOW interacts with two medication types: levodopa (used in Parkinson's disease) and thyroid hormones.
The most serious concern is a Moderate interaction with levodopa — tyrosine and levodopa compete for absorption in your small intestine, which could reduce how well levodopa works. If you take levodopa, separate your tyrosine dose from it by at least 2 hours.
Read the full breakdown — every affected drug type, severity by severity
Thyroid hormone medications also have a Moderate interaction with tyrosine. Since tyrosine is a building block for thyroid hormones, taking it alongside thyroid medication might add to the hormone's effects in your body.
Altogether, these interactions span 21 individual medications.
Run your exact medications through the checker on this page before you start. If you take either levodopa or thyroid hormones, talk it over with your doctor or pharmacist first — they can advise you on timing or whether this product is right for you.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Tyrosine 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-Tyrosine 500 mg interact with 21 drugs. Click any drug to see the details.
1 of the 1 ingredient in L-Tyrosine 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Tyrosine
Benserazide, LevodopaMadopar, Prolopa
How Benserazide, Levodopa interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineLevodopa Moderate
Interaction Summary
Theoretically, tyrosine might decrease the effectiveness of levodopa.
Read the full L-tyrosine + Benserazide, Levodopa interactionCarbidopa, LevodopaDhivy, Rytary, Sinemet, Sinemet CR
How Carbidopa, Levodopa interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineLevodopa Moderate
Interaction Summary
Theoretically, tyrosine might decrease the effectiveness of levodopa.
Read the full L-tyrosine + Carbidopa, Levodopa interactionCarbidopa, Levodopa, EntacaponeStalevo
How Carbidopa, Levodopa, Entacapone interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineLevodopa Moderate
Interaction Summary
Theoretically, tyrosine might decrease the effectiveness of levodopa.
Read the full L-tyrosine + Carbidopa, Levodopa, Entacapone interactionConjugated EstrogensCenestin, Enjuvia, Premarin, Premarin Vaginal Cream
How Conjugated Estrogens interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Conjugated Estrogens interactionDesiccated Thyroid ExtractWesthroid, WP Thyroid
How Desiccated Thyroid Extract interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Desiccated Thyroid Extract interactionDesiccated Thyroid Extract (prescription Drug)Nature-Throid, Thyrar
How Desiccated Thyroid Extract (prescription Drug) interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Desiccated Thyroid Extract (prescription Drug) interactionDextrothyroxineCholoxin
How Dextrothyroxine interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Dextrothyroxine interactionHuman Chorionic Gonadotropin (hcg)Pregnyl
How Human Chorionic Gonadotropin (hcg) interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Human Chorionic Gonadotropin (hcg) interactionLevodopaInbrija, Larodopa
How Levodopa interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineLevodopa Moderate
Interaction Summary
Theoretically, tyrosine might decrease the effectiveness of levodopa.
Read the full L-tyrosine + Levodopa interactionLevodopa, CarbidopaDuodopa
How Levodopa, Carbidopa interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineLevodopa Moderate
Interaction Summary
Theoretically, tyrosine might decrease the effectiveness of levodopa.
Read the full L-tyrosine + Levodopa, Carbidopa interactionLevothyroxineEltroxin, Estre, Euthyrox, Levo-T, Levolet, Levothroid +5 more
How Levothyroxine interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Levothyroxine interactionLevothyroxine SodiumErmez, Thyquidity, Tirosint-Sol
How Levothyroxine Sodium interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Levothyroxine Sodium interactionLevothyroxine, LiothyronineArmour Thyroid
How Levothyroxine, Liothyronine interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Levothyroxine, Liothyronine interactionLiothyronineCytomel
How Liothyronine interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Liothyronine interactionLiotrixEuthroid 1, Euthroid 1/2, Euthroid 3
How Liotrix interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Liotrix interactionLiotrix, T4/t3Euthroid 2
How Liotrix, T4/t3 interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Liotrix, T4/t3 interactionMenotropinsMenopur, Repronex
How Menotropins interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Menotropins interactionOspemifeneOsphena
How Ospemifene interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Ospemifene interactionTestosterone UndecanoateAndriol, Aveed, Jatenzo, Kyzatrex
How Testosterone Undecanoate interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Testosterone Undecanoate interactionThyroglobulinProloid
How Thyroglobulin interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Thyroglobulin interactionThyroid HormoneEtwon
How Thyroid Hormone interacts with L-Tyrosine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-tyrosineThyroid Hormone Moderate
Interaction Summary
Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Read the full L-tyrosine + Thyroid Hormone interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Tyrosine 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-Tyrosine
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.
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.
Brand information
Manufacturer and brand details for L-Tyrosine 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-Tyrosine 500 mg by NOW: Common Questions
Does L-Tyrosine 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-tyrosine and what does it do in my body?
Will L-tyrosine help me with memory or focus?
What side effects might I notice?
Is L-tyrosine safe to take while I'm pregnant or breastfeeding?
Can I take L-tyrosine if I have a thyroid condition?
Why would I separate this from levodopa by 2 hours?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Tyrosine 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-Tyrosine 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-Tyrosine 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 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
- 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.
- DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
- Wood DR, Reimherr FW, Wender PH. Amino acid precursors for the treatment of attention deficit disorder, residual type. Psychopharmacol Bull 1985;21:146-9.
- van Spronsen FJ, van Rijn M, Bekhof J. Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets. Am J Clin Nutr 2001;73:153-7. 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.
© 2021 Therapeutic Research Center, LLC