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Dietary supplement

Theanine Ingredients & Drug Interactions

by Thorne

Theanine label
See full label image
Capsule Category: Non-nutrient/non-botanical
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 Theanine 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

Theanine is a dietary supplement by Thorne 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 Suntheanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Theanine by Thorne

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

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HelloPharmacist Scorecard of Theanine by Thorne

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: Suntheanine, which is L-theanine, an amino acid found naturally in green tea. The capsule also holds a few inactive ingredients — hypromellose, leucine, calcium laurate, and microcrystalline cellulose — which help hold the capsule together and aid absorption.

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: Sleep and stress support.
  • We looked for evidence on: Insomnia, Stress, Generalized anxiety disorder (GAD), Cognitive function, Anxiety, Relaxation — and 1 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 Generalized anxiety disorder (GAD), Insomnia, Stress.

The evidence for theanine is mixed depending on what you're hoping it'll do. It's rated Possibly Effective for cognitive function — meaning there's some promise, but the research isn't airtight yet.

For age-related cognitive decline, Alzheimer disease, generalized anxiety disorder, obsessive-compulsive disorder, and cancer, we don't have enough reliable evidence to say whether it works or doesn't. If any of those last five are what you're after, talk with your pharmacist or doctor about whether the limited data makes sense for your situation.

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.

Theanine is generally well tolerated in healthy adults for short-term use, but we don't know much about what happens if you take it long-term. The most common side effects in trials were headaches, drowsiness, longer sleep, and more vivid dreams.

One child reported a subtle facial tic after starting 400 mg daily, though it stopped when she quit the supplement and she'd had tics before, so the link isn't clear. There isn't enough safety data in pregnancy or while breastfeeding, so the guidance is to avoid it during those times.

Talk with your doctor or pharmacist about your specific situation if you're pregnant, planning pregnancy, or nursing.

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 with us first — theanine can lower blood pressure further. Also double-check if you take any sedating medications (like sleep aids or anxiety meds) or serotonergic drugs (antidepressants and similar).

Use the search tool on this page to verify your exact medications before you start.

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.

Theanine might help with focus and mental clarity, and it's generally well tolerated short-term. If you take blood pressure medication, sedating drugs, or antidepressants, check with your pharmacist first — theanine can shift how those work.

We don't have long-term safety data, so this is best used short-term unless you've talked it over with your provider.

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 Sep 25, 2025.

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 Theanine, straight from the product label.

Brand Thorne
Barcode (UPC) 693749508014
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Sep 25, 2025
DSLD ID 336340
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), 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 Theanine by Thorne, 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:
1 Capsule(s)
Servings per container
90
UPC/BARCODE
693749508014
IngredientAmount% DV
Suntheanine200 mg--

Other ingredients: Hypromellose, Leucine, Calcium Laurate, Microcrystalline Cellulose

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

Sleep Stress

Gluten free

Suggested/Recommended/Usage/Directions

Suggested use: Take 1 capsule one to three times daily or as recommended by your health-care practitioner.

Precautions

Tamper evident: Use only if bottle is sealed.

If pregnant, consult your health-care practitioner before using this product.

Storage

Store tightly sealed in a cool, dry place.

Seals/Symbols

Manufactured in the USA using US & imported ingredients NSF Contents Certified

FDA Statement of Identity

Dietary Supplement

Brand IP Statement(s)

This product uses Taiyo International's Suntheanine (L-theanine). Suntheanine is a registered trademark of Taiyo International, Inc.

Formula

This product uses Taiyo International's Suntheanine (L-theanine). Suntheanine is a registered trademark of Taiyo International, Inc.

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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

See for yourself

Theanine by Thorne label

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

Theanine 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 Theanine by Thorne

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 container90 Amounts shown are per serving.

Suntheanine

Interacts with
565 drugs
200 mg per serving Form: L-Theanine

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...

Suntheanine monograph & interactions

Other (inactive) ingredients: Hypromellose, Leucine, Calcium Laurate, Microcrystalline Cellulose. These complete the product’s ingredient list but are not active constituents.

Interaction report

Theanine by Thorne Drug Interactions

Want to check YOUR meds against Theanine?

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

Suntheanine 565

Individual Drug Interactions

The ingredients in Theanine interact with 565 drugs. Click any drug to see the details.

1 of the 1 ingredient in Theanine interact with drugs. Each result below shows which ingredient is responsible. Suntheanine

Each ingredient & the kinds of drugs it affects

For each ingredient in Theanine 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.

Suntheanine3 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
Suntheanine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Theanine, from the product label.

Thorne

See all Thorne products
Name
Thorne Research, Inc.
Phone Number
1-800-228-1966
Pharmacist Counseling Corner

Theanine by Thorne: Common Questions

Does Theanine by Thorne interact with any medications?
Yes. Based on its ingredients, Theanine 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?
Theanine 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.
Can I take Theanine if I'm pregnant or breastfeeding?
There isn't enough safety data to know either way, so the guidance is to avoid it during pregnancy and while breastfeeding. Talk with your doctor or pharmacist about your specific situation if you're planning to use it at those times.
What side effects should I watch for?
Headaches, drowsiness, longer sleep, and more vivid dreams are the most commonly reported effects. One child experienced a facial tic on a high dose, though she'd had tics before and they stopped when she quit. Let your pharmacist know if you notice anything that concerns you.
How long can I safely take Theanine?
It's generally well tolerated in healthy adults for short-term use. Long-term safety hasn't been well studied, so it's best to talk with your doctor or pharmacist if you're thinking about using it long-term.
Does Theanine actually help with focus and anxiety?
There's some promise for cognitive function — it's rated Possibly Effective — but the research isn't solid yet. For anxiety disorders and age-related cognitive decline, we don't have enough reliable evidence to say whether it works.
What exactly is Suntheanine?
Suntheanine is a form of L-theanine, an amino acid naturally found in green tea. This product contains just that one active ingredient.

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.

Theanine label
Go deeper

The Full Monographs Behind Theanine’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

Theanine'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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