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Dietary supplement

L-Theanine 200 mg Ingredients & Drug Interactions

by Superior Source

L-Theanine 200 mg label
See full label image
Tablet Or Pill Category: Other Combinations
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 L-Theanine 200 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

The interaction bottom line Most serious interaction: Moderate

L-Theanine 200 mg is a dietary supplement by Superior Source with 2 active ingredients. Its ingredients are commonly taken for anxiety and stress, relaxation and calm, sleep support.Based on those ingredients, 651 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Theanine, Stevia leaf extract. 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 200 mg by Superior Source

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Theanine 200 mg by Superior Source — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Theanine 200 mg by Superior Source

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 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains 2 active ingredients. L-Theanine is an amino acid derived from tea that's thought to support calm focus, and stevia leaf extract is a natural sweetener.

The tablet also contains inactive ingredients — lactose and acacia gum — which are fillers and binders that hold the tablet together.

Does it work?

Not established
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
Not established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use.

Why this rating?
  • The label markets this product for: relaxation, stress relief, and sleep support.
  • We looked for evidence on: Generalized anxiety disorder (GAD), Stress, Insomnia, Anxiety, Calm, Sleep quality.
  • 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 Insomnia, Stress.

L-Theanine is possibly effective for supporting cognitive function. For age-related cognitive decline, Alzheimer disease, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), and cancer, the evidence we hold is insufficient to rate it.

Stevia's effectiveness for diabetes, high blood pressure, and obesity is also insufficient to rate in the data we have. In other words, the evidence for most of these uses hasn't been firmly established.

The evidence, ingredient by ingredient Theanine Stevia

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 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • 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, though long-term safety hasn't been well studied. Possible side effects include headaches, drowsiness, longer sleep, and increased dream activity.

Stevia is well tolerated in typical food amounts; purified stevia at supplement doses lacks good safety data, so use caution. Minor side effects like abdominal bloating, dizziness, headache, muscle pain, nausea, and numbness may occur but usually settle after the first week.

Allergic reactions are rare but possible. There isn't enough safety data to know whether L-Theanine or stevia are safe during pregnancy or while breastfeeding.

Talk with your doctor or pharmacist about whether this product is right for you if you're pregnant, planning to become pregnant, or breastfeeding.

Side effects, ingredient by ingredient Theanine Stevia

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?
  • 2 of the 2 matched ingredients can interact with medications — Stevia, Theanine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: diabetes medications; lithium.
  • For scale: 651 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.

Double-check this product before starting if you take blood pressure medications (antihypertensives) — L-Theanine and stevia both may lower your blood pressure further. If you take lithium for bipolar disorder or depression, stevia might raise your lithium levels.

Diabetes medications and CNS depressants (like sleeping pills or anxiety drugs) may also be affected — run these through the checker below with your own doctor or pharmacist.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Moderate medication interactions have been identified, and safety information is well characterized.

L-Theanine 200 mg may help with focus and mental clarity, but evidence for many other uses is still weak. If you take blood pressure medication, lithium, diabetes drugs, or sedatives, check your exact medications with the tool on this page before starting — your doctor or pharmacist can help you weigh the risks.

Pregnancy and breastfeeding safety data are thin, so discuss this with your healthcare provider if that applies to you.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 2 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 25, 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 200 mg, straight from the product label.

Brand Superior Source
Net contents 100 MicroLingual(R) Instant Dissolve Tablet(s)
Market status On market
Date entered into DSLD Jan 25, 2020
DSLD ID 212697
Product type Other Combinations
Supplement form Tablet Or Pill
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
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 200 mg by Superior Source, 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:
2 MicroLingual(R) Tablet(s)
Maximum serving Sizes:
2 MicroLingual(R) Tablet(s)
Servings per container
50
IngredientAmount% DV
L-Theanine200 mg--
Stevia leaf extract2 mg--

Other ingredients: Lactose, Acacia Gum

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.
Suggested/Recommended/Usage/Directions

Directions: As a dietary supplement, dissolve two Microlingual tablets under the tongue as directed by your healthcare provider (physician). This product may also be swallowed.

Formulation

GMO free

FDA Statement of Identity

Dietary Supplement

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

See for yourself

L-Theanine 200 mg by Superior Source label

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

L-Theanine 200 mg 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 200 mg by Superior Source

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 MicroLingual(R) Tablet(s) Dosage formTablet Or Pill Servings per container50 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

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

Stevia leaf extract

Interacts with
259 drugs
2 mg per serving

Stevia is a plant-based, calorie-free sweetener that is widely used as a sugar alternative and is considered safe in normal food amounts by major regu...

Stevia leaf extract monograph & interactions

Other (inactive) ingredients: Lactose, Acacia Gum. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Theanine 200 mg by Superior Source Drug Interactions

Want to check YOUR meds against L-Theanine 200 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 checker
651Drugs
173 Moderate 478 Minor

Ingredients driving the most interactions

L-Theanine 565
Stevia leaf extract 259

Individual Drug Interactions

The ingredients in L-Theanine 200 mg interact with 651 drugs. Click any drug to see the details.

2 of the 2 ingredients in L-Theanine 200 mg interact with drugs. Each result below shows which ingredient is responsible. L-Theanine Stevia leaf extract

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Theanine 200 mg with known interactions, here are the types of medications they 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

Stevia leaf extract3 drug types · 259 drugs

Lithium

Theoretically, stevia might decrease clearance and increase levels of lithium.
Animal research suggests that stevia extracts might have diuretic activity. Theoretically, increased reabsorption of lithium along with sodium might reduce excretion and increase levels of lithium.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, stevia might increase the risk for hypoglycemia when combined with antidiabetes drugs.
Preliminary clinical research in patients with type 2 diabetes suggests that taking a single dose of stevia extract 1000 mg reduces postprandial blood glucose levels when taken with a meal. However, other clinical research in patients with type 1 or type 2 diabetes suggests that taking stevioside 250 mg three times daily does not significantly affect blood glucose levels or glycated hemoglobin (HbA1C) after three months of treatment.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, combining stevia or stevia constituents with antihypertensive agents might increase the risk of hypotension.
Stevia extract and stevioside might lower blood pressure in patients with hypertension. However, other clinical research suggests that stevioside does not significantly lower blood pressure in patients with hypertension.

Likelihood Possible Evidence D
Stevia leaf extract full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Theanine 200 mg, from the product label.

Superior Source

See all Superior Source products
Name
Superior Source
Phone Number
800-421-6175
Web Address
www.superiorsourcevitamins.com
Pharmacist Counseling Corner

L-Theanine 200 mg by Superior Source: Common Questions

Does L-Theanine 200 mg by Superior Source interact with any medications?
Yes. Based on its ingredients, L-Theanine 200 mg has a known interaction with 651 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Theanine 200 mg contains 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is 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 L-Theanine 200 mg if I'm pregnant or breastfeeding?
There isn't enough safety data for either L-Theanine or stevia during pregnancy or while breastfeeding. Talk with your doctor or pharmacist before taking this product in either situation — they can give you personalized advice based on your health.
What side effects might I notice?
L-Theanine may cause headaches, drowsiness, longer sleep, or more vivid dreams. Stevia might cause abdominal bloating, dizziness, headache, muscle pain, nausea, or numbness, but these usually fade after the first week. Allergic reactions are rare.
Does L-Theanine actually help with focus and thinking?
It's possibly effective for cognitive function, meaning there's some evidence it may help, but the research isn't conclusive. For other uses like anxiety or age-related memory loss, we don't have enough reliable evidence to say whether it works.
Is this product safe to use long-term?
L-Theanine is generally well tolerated for short-term use in healthy adults, but long-term safety hasn't been well studied. Stevia at supplement doses also lacks good long-term safety data. If you're thinking about taking it for weeks or months, talk it over with your doctor or pharmacist.
Why does this tablet contain stevia? I thought it was just L-Theanine.
Stevia is used here as a sweetener to improve taste. It's the inactive sweetening ingredient, not an active part of what the product aims to do — though it does have its own interactions you should be aware of.

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 200 mg label
Go deeper

The Full Monographs Behind L-Theanine 200 mg’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 → Herb & supplement monograph

Stevia

Interacts with 259 drugs

Stevia is a plant-based, calorie-free sweetener that is widely used as a sugar alternative and is considered safe in normal food amounts by major regulators. Purified stevia extracts have a...

Read the full Stevia monograph →
Sources

Sources & How We Checked

L-Theanine 200 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.

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 16 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 →

Stevia 10 references
  1. Chan P, Xu DY, Liu JC, et al. The effect of stevioside on blood pressure and plasma catecholamines in spontaneously hypertensive rats. Life Sci 1998;63:1679-84. PubMed
  2. Melis MS. A crude extract of Stevia rebaudiana increases the renal plasma flow of normal and hypertensive rats. Braz J Med Biol Res 1996;29:669-75.
  3. Melis MS. Chronic administration of aqueous extract of Stevia rebaudiana in rats: renal effects. J Ethnopharmacol 1995;47:129-34. PubMed
  4. Melis MS, Sainati AR. Effect of calcium and verapamil on renal function of rats during treatment with stevioside. J Ethnopharmacol 1991;33:257-622. PubMed
  5. Hsieh MH, Chan P, Sue YM, et al. Efficacy and tolerability of oral stevioside in patients with mild essential hypertension: a two-year, randomized, placebo-controlled study. Clin Ther 2003;25:2797-808. PubMed
  6. Chan P, Tomlinson B, Chen YJ, et al. A double-blind placebo-controlled study of the effectiveness and tolerability of oral stevioside in human hypertension. Br J Clin Pharmacol 2000;50:215-20. PubMed
  7. Gregersen S, Jeppesen PB, Holst JJ, Hermansen K. Antihyperglycemic effects of stevioside in type 2 diabetic subjects. Metabolism 2004;53:73-6. PubMed
  8. Barriocanal LA, Palacios M, Benitez G, et al. Apparent lack of pharmacological effect of steviol glycosides used as sweeteners in humans. A pilot study of repeated exposures in some normotensive and hypotensive individuals and in Type 1 and Type 2 diabeti
  9. Ferri LA, Alves-Do-Prado W, Yamada SS, et al. Investigation of the antihypertensive effect of oral crude stevioside in patients with mild essential hypertension. Phytother Res 2006;20:732-6. PubMed
  10. Almiron-Roig E, Navas-Carretero S, Castelnuovo G, et al. Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEE

See these in context on the Stevia 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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