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Dietary supplement

L-Theanine Powder Ingredients & Drug Interactions

by Nootropics Depot

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 Nootropics Depot 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 L-Theanine Powder by Nootropics Depot

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

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HelloPharmacist Scorecard of L-Theanine Powder by Nootropics Depot

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 product contains one active ingredient: L-theanine, an amino acid found naturally in tea. It's included here as a pure powder form.

There are no inactive ingredients listed for this product.

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

This product doesn't appear to be marketed for a specific use, so we graded Theanine's overall clinical evidence instead.

Moderate

Some clinical evidence supports Theanine for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Cognitive function — rated "Possibly Effective" (Natural Medicines).

L-theanine is possibly effective for supporting cognitive function. For other uses—age-related mental decline, Alzheimer disease, generalized anxiety, obsessive-compulsive disorder, and cancer—the evidence we hold is insufficient to make a rating, so we can't say whether it works for those purposes.

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 when used short-term, but long-term safety hasn't been well studied. Some people report headaches, drowsiness, longer sleep, or more vivid dreams after taking it orally.

One case of facial tics was reported in a child taking 400 mg daily, though the tics stopped once the supplement was discontinued—and that child had a history of tics, so the link wasn't clear. There isn't enough safety data to know how L-theanine affects a developing baby or a breastfeeding infant, so the data advises against use during pregnancy and while breastfeeding.

Talk with your doctor or pharmacist about whether it's right for your situation.

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.

Before you start L-theanine, check with your doctor or pharmacist if you take blood pressure medications (antihypertensive drugs)—theanine could lower your pressure further. Also double-check if you're on any central nervous system depressants like sleep aids or sedating pain relievers, or on serotonergic drugs like antidepressants, even though those last two are lower-risk concerns.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

L-theanine may help with focus and mental clarity if the evidence holds up for you. If you take blood pressure medication or sleep aids, check with your doctor or pharmacist first—theanine can lower blood pressure and add to sedation.

It's generally well tolerated short-term, but long-term safety isn't established. Avoid it during pregnancy and breastfeeding unless your healthcare provider advises otherwise.

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 Aug 23, 2020.

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 Nootropics Depot
Net contents 4.4 Ounce(s); 125 Gram(s)
Market status On market
Date entered into DSLD Aug 23, 2020
DSLD ID 232363
Product type Non-nutrient/non-botanical
Supplement form Powder
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Women (not pregnant or lactating)
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 Nootropics Depot, 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:
0.1 Gram(s)
Maximum serving Sizes:
0.1 Gram(s)
Servings per container
1250
IngredientAmount% DV
L-Theanine100 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.
FDA Statement of Identity

Dietary Supplement

Precautions

Disclaimer: Always consult with a qualified health physician before taking any new dietary supplement.

Warning: Keep out of reach of children. Do not take this or any other supplement if under the age of 18, pregnant or nursing a baby, or if you have any known or suspected medical conditions, and/or taking prescription drug(s) or OTC medication(s).

Do not take this or any other supplement if under the age of 18, pregnant or nursing a baby, or if you have any known or suspected medical conditions, and/or taking prescription drug(s) or OTC medication(s).

FDA Disclaimer Statement

This product is not intended to diagnose, treat, cure or prevent any diseases. These statements have not been evaluated by the Food & Drug Administration.

Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement, take 100mg 1-2 times daily.

Storage

Storage: Store in a cool and dry place. Keep away from direct sunlight and heat.

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

See for yourself

L-Theanine Powder by Nootropics Depot 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 Nootropics Depot

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

Serving size0.1 Gram(s) Dosage formPowder Servings per container1250 Amounts shown are per serving.

L-Theanine

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 monograph & interactions
Interaction report

L-Theanine Powder by Nootropics Depot 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 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

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-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 L-Theanine Powder, from the product label.

Nootropics Depot

See all Nootropics Depot products
Name
Nootropics Depot
Street Address
8380 S. Kyrene Rd. Ste. 110
City
Tempe
State
AZ
ZipCode
85284
Web Address
nootropicsdepot.com
Pharmacist Counseling Corner

L-Theanine Powder by Nootropics Depot: Common Questions

Does L-Theanine Powder by Nootropics Depot 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.
Can I take this if I'm pregnant or breastfeeding?
There isn't enough safety data to know either way. The safety information advises against taking L-theanine during pregnancy and while breastfeeding. Talk with your doctor or pharmacist for personalized advice.
What are the most common side effects?
L-theanine is generally well tolerated, but some people report headaches, drowsiness, longer sleep, or more vivid dreams. These aren't severe, but they're worth knowing about if they sound like something you'd want to avoid.
Does L-theanine actually work for focus and brain function?
The evidence says it's possibly effective for cognitive function. For other brain-related uses like age-related decline or Alzheimer disease, the evidence we have is too limited to say whether it works.
How long is it safe to take this?
L-theanine is generally well tolerated for short-term use in healthy adults, but long-term safety hasn't been well studied. If you're thinking about taking it regularly, check with your doctor or pharmacist first.
What is L-theanine, and where does it come from?
L-theanine is an amino acid found naturally in tea. This powder gives you a concentrated form of it on its own.

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

Not sure if L-Theanine Powder is safe with your meds?

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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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