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Dietary supplement

L-Theanine Powder Ingredients & Drug Interactions

by Herbadiet

L-Theanine Powder label
See full label image
Powder 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 L-Theanine Powder 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-Theanine Powder is a dietary supplement by Herbadiet 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 powder. 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-Theanine Powder by Herbadiet

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

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HelloPharmacist Scorecard of L-Theanine Powder by Herbadiet

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 powder contains one active ingredient: L-theanine, an amino acid found naturally in tea. There are no other active ingredients and no inactive fillers listed.

Does it work?

Insufficient 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
Insufficient

There isn't enough reliable clinical evidence to rate this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: Stress and anxiety management.
  • We looked for evidence on: Generalized anxiety disorder (GAD), Stress, Anxiety, Relaxation, Calm.
  • The closest evidence on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Generalized anxiety disorder (GAD) (Natural Medicines).
  • Also on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Stress.

L-theanine has possibly effective evidence for cognitive function — meaning some research supports its use, but the evidence isn't rock-solid yet. For age-related cognitive decline, Alzheimer disease, generalized anxiety, OCD, and cancer, the evidence we hold is insufficient to rate whether it works.

If you're considering it for any of those, talk with your doctor about what the current research 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 long-term safety hasn't been well studied, so we don't have a clear picture of what happens if you take it for years. The most common side effects reported are headaches and drowsiness; some people also noticed increased sleep duration or more vivid dreams.

One case of a facial tic in a child was reported after starting 400 mg daily, but the child had a history of tics and they stopped when theanine was discontinued, so the link is unclear. The safety data advises against use during pregnancy and breastfeeding because there isn't enough information to know it's safe for you or your baby.

If you're pregnant, planning pregnancy, or nursing, talk with your doctor or pharmacist before taking this product.

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 before adding this product if you take blood pressure medications — theanine might lower your pressure further and require a dose adjustment. Also flag it if you're on sedatives, sleep aids, or other CNS depressants, or on any antidepressant or serotonergic drug, and let your doctor or pharmacist know you're considering L-theanine.

Check your own medication Run your meds through the checker above

The bottom line

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

L-Theanine Powder is a single, straightforward supplement that may help with focus and mental clarity, though the evidence is modest. If you take blood pressure medication, sedatives, or antidepressants, you'll want to check with your doctor or pharmacist before starting it.

Pregnant or nursing? There's not enough safety data, so it's best to skip it and discuss options with your healthcare 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 Jun 22, 2023.

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-Theanine Powder, straight from the product label.

Brand Herbadiet
Net contents 0 Not Present
Market status On market
Date entered into DSLD Jun 22, 2023
DSLD ID 293722
Product type Non-nutrient/non-botanical
Supplement form Powder
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), 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-Theanine Powder by Herbadiet, 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:
100 mg
Maximum serving Sizes:
200 mg
IngredientAmount% DV
L-Theanine powder100 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.
Formulation

Stress & anxiety management

Free of fillers, binders, artificial ingredients, dairy, soy, wheat, gluten, yeast

Being a natural produce, there can be minor color variations because of geographical & seasonal variation of the raw material. Supplements can be hygroscopic & may agglomerate at times. This, in no way, affect the efficacy of the product.

V Vegan

Ethically sourced Scientifically tested Premium grade ingredients

Formula

Amino acid

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions: As a dietary supplement, take up to 200 mg, or as directed by your physician.

Precautions

Keep out of reach of children.

Pregnant or lactating women should consult your physician before use.

Storage

Store in a dry, cool & dark.

FDA Disclaimer Statement

Warning: 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.

Seals/Symbols

FSSAI (Food Safety and Standards Authority of India) Lic. No.: 20817018000147

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

See for yourself

L-Theanine Powder by Herbadiet label

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

L-Theanine Powder 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-Theanine Powder by Herbadiet

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

Serving size100 mg Dosage formPowder Amounts shown are per serving.

L-Theanine powder

Interacts with
565 drugs
100 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 powder monograph & interactions
Interaction report

L-Theanine Powder by Herbadiet Drug Interactions

Want to check YOUR meds against L-Theanine Powder?

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 powder 565

Individual Drug Interactions

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

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

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Theanine Powder 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-Theanine powder3 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 powder full monograph & interactions
The maker

Brand information

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

Herbadiet

See all Herbadiet products
Name
Arkure Health Care
Street Address
11, Sector - 14
City
Rohtak
State
Haryana
ZipCode
124001
Web Address
www.herbadiet.in
Pharmacist Counseling Corner

L-Theanine Powder by Herbadiet: Common Questions

Does L-Theanine Powder by Herbadiet interact with any medications?
Yes. Based on its ingredients, L-Theanine Powder 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?
L-Theanine Powder 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.
Will L-theanine make me drowsy?
Some people have reported drowsiness after taking it, along with increased sleep duration and more vivid dreams. It's not a universal effect, but if you're sensitive to sedation or already take sleep aids, mention this to your pharmacist before trying it.
Can I take L-theanine while pregnant or breastfeeding?
No — there isn't enough safety data to know it's safe during pregnancy or while breastfeeding. Talk with your doctor or pharmacist about whether it's right for you in either situation.
How long is it safe to take L-theanine?
It's generally well tolerated for short-term use in healthy adults. Long-term safety hasn't been well studied, so if you're thinking of taking it regularly for months or longer, check with your doctor or pharmacist first.
Is L-theanine proven to help with anxiety or focus?
For cognitive function, there's possibly effective evidence — meaning some research supports it, but it's not bulletproof. For anxiety disorders like GAD or OCD, the evidence we hold is too thin to say whether it works. Your doctor can discuss what current research shows.
What side effects should I watch for?
Headaches and drowsiness are the most common reports. Some people noticed more vivid dreams or longer sleep. If you have unusual side effects, stop and talk to your pharmacist.

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-Theanine Powder label
Go deeper

The Full Monographs Behind L-Theanine Powder’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

L-Theanine Powder'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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