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Dietary supplement

100% Pure L-Theanine 200 Milligrams Ingredients & Drug Interactions

by NutraBio

100% Pure L-Theanine 200 Milligrams label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking 100% Pure L-Theanine 200 Milligrams 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

100% Pure L-Theanine 200 Milligrams is a dietary supplement by NutraBio with 1 active ingredient. Its ingredients are commonly taken for anxiety and stress, relaxation and calm, sleep support.Based on those ingredients, 565 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Theanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against 100% Pure L-Theanine 200 Milligrams by NutraBio

Ask about any prescription or over-the-counter medication and we check it for interactions with 100% Pure L-Theanine 200 Milligrams by NutraBio — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of 100% Pure L-Theanine 200 Milligrams by NutraBio

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-Theanine, an amino acid sourced from tea leaves that works on brain chemistry. The capsule itself is made from vegetable material — there are no fillers or extra additives.

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: relaxation, calm, focus and sleep support.
  • We looked for evidence on: Stress, Generalized anxiety disorder (GAD), Insomnia, Cognitive function, Attention deficit-hyperactivity disorder (ADHD), anxiety — and 3 related terms.
  • The strongest evidence on file: Theanine is rated "Possibly Effective" for Cognitive function (Natural Medicines).
  • Also on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Anxiety, Attention deficit-hyperactivity disorder (ADHD), Generalized anxiety disorder (GAD), Insomnia, and more.

The evidence here is mixed. L-Theanine is possibly effective for supporting cognitive function, so if you're looking for a mental-clarity edge, there's some backing for that.

For age-related cognitive decline, Alzheimer's disease, generalized anxiety disorder, obsessive-compulsive disorder, and cancer, the evidence we hold isn't reliable enough to say whether it works. If those are your concerns, you'll want to talk with your doctor about what the current research really shows.

The evidence, ingredient by ingredient Theanine

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-Theanine is generally well tolerated in healthy adults for short-term use, but we don't have good long-term safety data, so taking it for months or years is less clear. The most common side effect is headache; some people also report drowsiness, longer sleep, and more vivid dreams.

One child on a much higher dose (400 mg daily) developed facial tics within four days, though they stopped when she quit — but she'd had tics before, so the link wasn't certain. There isn't enough safety data to know whether L-Theanine is safe in pregnancy or while breastfeeding, so the guidance is to avoid it during those times.

If you're pregnant, planning to become pregnant, or nursing, talk with your doctor or pharmacist before starting.

Side effects, ingredient by ingredient Theanine

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 — Theanine.
  • The most serious interaction on file is rated Moderate.
  • For scale: 565 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 your blood pressure medications first — L-Theanine can strengthen their effect. Also run any sedating drugs (sleep aids, some anxiety or pain meds) and serotonergic antidepressants or migraine drugs through the checker to be safe, though the latter two carry Minor risk and no real-world cases of harm.

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-Theanine is a single, straightforward supplement possibly useful for cognitive sharpness in healthy adults. If you take blood pressure medication, sleep aids, or antidepressants, check with us first — this ingredient can potentiate some of them.

Long-term safety isn't well established, so it's mainly a short-term tool. Ask your pharmacist whether it fits your situation.

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 Oct 22, 2015.

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 100% Pure L-Theanine 200 Milligrams, straight from the product label.

Brand NutraBio
Barcode (UPC) 649908245168
Net contents 90 Cap(s)
Market status On market
Date entered into DSLD Oct 22, 2015
DSLD ID 51093
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Kosher, No Allergies, Gluten 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 100% Pure L-Theanine 200 Milligrams by NutraBio, 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 Vegetable Capsule(s)
Maximum serving Sizes:
1 Vegetable Capsule(s)
Servings per container
90
UPC/BARCODE
649908245168
IngredientAmount% DV
L-Theanine200 mg--

Other ingredients: Vegetable Capsule

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

Non-GMO Gluten Free BSE/TSE Free

No Fillers No Excipients No Additives

Free of Harmful Impurities.

Vegetarian

Precautions

Warning: Not intended for use by persons under the age of 18. Keep out of the reach of children.

If you are pregnant, breast feeding, have known medical conditions (including kidney or liver disease) or are taking prescription or OTC medication(s) consult with your health care practitioner before using this product.

General Statements

Manufactured in a GMP & FDA inspected facility

Free Form Amino Acid

Pharmaceutical Grade. HPLC Lab tested for potency.

90 servings 200 milligrams

Made in a GMP & FDA inspected facility

Vegetable Capsule

Made in USA

Brand IP Statement(s)

Amino Therapy

Seals/Symbols

TRUE LABEL FULL LABEL DISCLOSURE

OU

FDA Statement of Identity

Dietary Supplement

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.

General

24516-000 B20448-000

Formula

Allergen Free

Suggested/Recommended/Usage/Directions

1 capsule 1x daily with food Suggested Use: As a dietary supplement, take 1 capsule daily, preferably with a meal, or as directed by your physician.

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

See for yourself

100% Pure L-Theanine 200 Milligrams by NutraBio label

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

100% Pure L-Theanine 200 Milligrams 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 100% Pure L-Theanine 200 Milligrams by NutraBio

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

Serving size1 Vegetable Capsule(s) Dosage formCapsule Servings per container90 Amounts shown are per serving.

L-Theanine

Interacts with
565 drugs
200 mg per serving

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong dro...

L-Theanine monograph & interactions

Other (inactive) ingredients: Vegetable Capsule. These complete the product’s ingredient list but are not active constituents.

Interaction report

100% Pure L-Theanine 200 Milligrams by NutraBio Drug Interactions

Want to check YOUR meds against 100% Pure L-Theanine 200 Milligrams?

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
565Drugs
172 Moderate 393 Minor

Ingredients driving the most interactions

L-Theanine 565

Individual Drug Interactions

The ingredients in 100% Pure L-Theanine 200 Milligrams interact with 565 drugs. Click any drug to see the details.

1 of the 1 ingredient in 100% Pure L-Theanine 200 Milligrams interact with drugs. Each result below shows which ingredient is responsible. L-Theanine

Each ingredient & the kinds of drugs it affects

For each ingredient in 100% Pure L-Theanine 200 Milligrams 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-Theanine3 drug types · 565 drugs

Antihypertensive Drugs

Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Animal research shows that theanine can lower blood pressure in spontaneously hypertensive animals. Theoretically, concomitant use of theanine and antihypertensive drugs might potentiate the antihypertensive activity.

Likelihood Possible Evidence D
Cns Depressants

Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Theoretically, theanine may compete with glutamate and/or increase plasma gamma-aminobutyric acid (GABA) levels, which could cause CNS depression. In one clinical study, some subjects taking oral theanine reported drowsiness.

Likelihood Unlikely Evidence D
Serotonergic Drugs

Clinical studies regarding the effects of L-theanine on serotonin levels are conflicting. Some studies suggest it can increase serotonin levels in the brain while others report that it may decrease them. Nevertheless, there have been no reports of l-theanine being a causative agent in serotonergic-related side effects or serotonin syndrome.

Likelihood Unlikely Evidence C
L-Theanine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for 100% Pure L-Theanine 200 Milligrams, from the product label.

NutraBio

See all NutraBio products
Name
NutraBio Labs, Inc.
Street Address
564 Lincoln Blvd.
City
Middlesex
State
NJ
ZipCode
08846
Phone Number
732-748-8606
Web Address
www.nutrabio.com
Pharmacist Counseling Corner

100% Pure L-Theanine 200 Milligrams by NutraBio: Common Questions

Does 100% Pure L-Theanine 200 Milligrams by NutraBio interact with any medications?
Yes. Based on its ingredients, 100% Pure L-Theanine 200 Milligrams has a known interaction with 565 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
100% Pure L-Theanine 200 Milligrams 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-Theanine, and what does it do?
L-Theanine is an amino acid found naturally in tea. It works on brain chemistry and is possibly effective for cognitive function — that's the one area with solid evidence backing. For anxiety, memory loss, and other conditions, the evidence isn't reliable enough yet.
Can I take this if I'm on blood pressure medication?
Not without checking first. L-Theanine can lower blood pressure itself, so combined with your medication it might drop too far. Run your specific drug through our interaction tool or ask your pharmacist before starting.
What side effects might I notice?
Headache is the most common. Some people also feel drowsy, sleep longer, or have more vivid dreams. These effects are usually mild, but if they bother you or don't go away, stop taking it and talk to us.
Is it safe to take while I'm pregnant or breastfeeding?
There isn't enough safety data to know either way. The guidance is to avoid it during pregnancy and while breastfeeding. If you're in one of those situations, talk with your doctor or pharmacist for personalized advice.
How long can I take L-Theanine safely?
It's generally well tolerated for short-term use in healthy adults, but we don't have good long-term safety data. If you're thinking of taking it for months or longer, check in with your pharmacist about what that means for you.

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.

100% Pure L-Theanine 200 Milligrams label
Go deeper

The Full Monographs Behind 100% Pure L-Theanine 200 Milligrams’s Ingredients

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

Herb & supplement monograph

Theanine

Interacts with 565 drugs

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong drowsiness. Early research suggests it may...

Read the full Theanine monograph →
Sources

Sources & How We Checked

100% Pure L-Theanine 200 Milligrams'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 6 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.

Theanine 6 references
  1. Yokogoshi H, Kobayashi M. Hypotensive effect of gamma-glutamylethylamide in spontaneously hypertensive rats. Life Sci 1998;62:1065-8.
  2. Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., and Scholey, A. B. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol.Psychol. 2008;77(2):113-122. PubMed
  3. Yokogoshi, H., Kato, Y., Sagesaka, Y. M., Takihara-Matsuura, T., Kakuda, T., and Takeuchi, N. Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci.Biotechnol.Biochem. 1995;59(4):615-618. PubMed
  4. Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011;16(4):348-
  5. Hidese S, Ota M, Wakabayashi C, et al. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr 2017;29(2):72-9.
  6. Tsuchiya T, Honda H, Oikawa M, et al. Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients. Int J Clin Oncol 2016;21(6):1085-90. PubMed

See these in context on the Theanine 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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