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Dietary supplement

L-Theanine 200 mg Plus Gaba 100 mg Ingredients & Drug Interactions

by Dr. Mercola

L-Theanine 200 mg Plus Gaba 100 mg label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Theanine 200 mg Plus Gaba 100 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 Plus Gaba 100 mg is a dietary supplement by Dr. Mercola with 2 active ingredients. Its ingredients are commonly taken for anxiety and stress, sleep problems, relaxation.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, Gamma Aminobutyric Acid. 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 Plus Gaba 100 mg by Dr. Mercola

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola

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 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 (sold under the brand name Suntheanine here) at 200 mg and GABA (gamma-aminobutyric acid) at 100 mg. Both are amino acids your brain naturally makes; the supplement form is meant to supplement what you produce on your own.

The inactive ingredients are microcrystalline cellulose, ascorbyl palmitate, hydroxypropyl methylcellulose, and silicon dioxide — standard capsule fillers and preservatives.

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: Anxiety, stress, relaxation and sleep support.
  • We looked for evidence on: Anxiety, Generalized anxiety disorder (GAD), Stress, Insomnia, Post-traumatic stress disorder (PTSD), Relaxation — and 2 related terms.
  • The closest evidence on file: Gamma-aminobutyric Acid (gaba) is rated "Insufficient Reliable Evidence To Rate" for Anxiety (Natural Medicines).
  • Also on file: Gamma-aminobutyric Acid (gaba) is rated "Insufficient Reliable Evidence To Rate" for Insomnia, Post-traumatic stress disorder (PTSD).
  • Also on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Generalized anxiety disorder (GAD), Insomnia, Stress.

For L-theanine, the evidence supports it as possibly effective for cognitive function — meaning some solid science backs it for thinking and focus. For everything else listed (age-related cognitive decline, Alzheimer's disease, generalized anxiety, obsessive-compulsive disorder, and cancer), the evidence isn't strong enough yet to rate it.

For GABA, the evidence is weaker. Conditions like anxiety, ADHD, chronic bronchitis, athletic performance, cerebral palsy, and others have insufficient evidence — meaning we don't have solid data showing it works for these uses.

Neither ingredient has established effectiveness for anxiety specifically, even though that's a common reason people take them.

The evidence, ingredient by ingredient Gamma-aminobutyric Acid (gaba) 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 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.

Both ingredients are generally well tolerated for short-term use, but long-term safety hasn't been well studied — so if you're thinking about taking this for months or longer, that's a conversation to have with your pharmacist. The most common side effects from L-theanine are headaches, drowsiness, and more vivid dreams.

From GABA, you might experience drowsiness, nausea, stomach upset, minor throat burning, or muscle weakness. One case of a temporary menstrual change was reported with GABA, and there's one old report of a tic in a child, though it wasn't clearly linked to the supplement.

The safety data for pregnancy and breastfeeding isn't solid enough to recommend either ingredient — both labels say to avoid during pregnancy and to avoid while breastfeeding. If you're pregnant or nursing, talk with your doctor or pharmacist before taking this.

Side effects, ingredient by ingredient Gamma-aminobutyric Acid (gaba) 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?
  • 2 of the 2 matched ingredients can interact with medications — Gamma-aminobutyric Acid (gaba), 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, check any blood pressure medications you're on — both ingredients could lower your pressure further. Also flag any sedating drugs (sleep aids, anti-anxiety meds, antihistamines, or pain relievers that make you drowsy).

If you take antidepressants, mention those too, especially SSRIs, because L-theanine's effect on serotonin is documented even though serious problems haven't been reported.

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.

This product might help with thinking and focus if you're looking for that specific benefit, but the anxiety claims aren't backed by strong evidence. If you take blood pressure medication or any sedating drugs, you need to check with us first — the interactions are real.

It's generally well tolerated short-term, but we don't know much about long-term use, so talk with your pharmacist about how long you're planning to take it.

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 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 L-Theanine 200 mg Plus Gaba 100 mg, straight from the product label.

Brand Dr. Mercola
Barcode (UPC) 810094213503
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Sep 25, 2025
DSLD ID 339487
Product type Non-nutrient/non-botanical
Supplement form Capsule
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 Plus Gaba 100 mg by Dr. Mercola, 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 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
30
UPC/BARCODE
810094213503
IngredientAmount% DV
Gamma Aminobutyric Acid100 mg--
Suntheanine200 mg--

Other ingredients: Microcrystalline Cellulose, Ascorbyl Palmitate, Hydroxypropyl Methylcellulose, Silicon Dioxide

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

Suggested use: Adults, as a dietary supplement, take two (2) capsules daily.

Precautions

Keep out of reach of children.

Do not use if safety seal is broken.

If you are nursing, pregnant, taking medication or have a medical condition, consult your physician before taking this product.

Formula

200 mg L-Theanine & 100 mg GABA Per Serving

FDA Statement of Identity

Dietary Supplement

General Statements

Providing quality products since 2001.

Brand IP Statement(s)

Suntheanine is a registered trademark of Taiyo International, Inc.

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

See for yourself

L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola label

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

L-Theanine 200 mg Plus Gaba 100 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 Plus Gaba 100 mg by Dr. Mercola

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

Serving size2 Capsule(s) Dosage formCapsule Servings per container30 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.

Gamma Aminobutyric Acid

Interacts with
419 drugs
100 mg per serving

GABA is a calming chemical messenger (neurotransmitter) that your body makes on its own, and it is sold as a supplement for stress, anxiety, and sleep...

Gamma Aminobutyric Acid monograph & interactions

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: Microcrystalline Cellulose, Ascorbyl Palmitate, Hydroxypropyl Methylcellulose, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola Drug Interactions

Want to check YOUR meds against L-Theanine 200 mg Plus Gaba 100 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
565Drugs
172 Moderate 393 Minor

Ingredients driving the most interactions

Suntheanine 565
Gamma Aminobutyric Acid 419

Individual Drug Interactions

The ingredients in L-Theanine 200 mg Plus Gaba 100 mg interact with 565 drugs. Click any drug to see the details.

2 of the 2 ingredients in L-Theanine 200 mg Plus Gaba 100 mg interact with drugs. Each result below shows which ingredient is responsible. Suntheanine Gamma Aminobutyric Acid

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Theanine 200 mg Plus Gaba 100 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.

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

Gamma Aminobutyric Acid2 drug types · 419 drugs

Antihypertensive Drugs

Theoretically, taking GABA with antihypertensive drugs might increase the risk of hypotension.
Some clinical research shows that GABA can decrease blood pressure in patients with hypertension.

Likelihood Possible Evidence B
Cns Depressants

Theoretically, GABA might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Endogenous GABA has well-established relaxant effects and GABA(A) receptors have an established physiological role in sleep. However, the effects of GABA supplements are unclear, as it is unknown whether exogenous GABA crosses the blood-brain barrier. Although there have been limited reports of drowsiness or tiredness with GABA supplements, these effects have not been widely reported in clinical studies. Additionally, intravenous GABA 0.1-1 mg/kg has been shown to induce anxiety in a dose-dependent manner.

Likelihood Unlikely Evidence D
Gamma Aminobutyric Acid full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Theanine 200 mg Plus Gaba 100 mg, from the product label.

Dr. Mercola

See all Dr. Mercola products
Name
NHP
Street Address
125 SW 3rd Place
City
Cape Coral
State
FL
ZipCode
33991
Phone Number
(877) 985-2696
Pharmacist Counseling Corner

L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola: Common Questions

Does L-Theanine 200 mg Plus Gaba 100 mg by Dr. Mercola interact with any medications?
Yes. Based on its ingredients, L-Theanine 200 mg Plus Gaba 100 mg 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 200 mg Plus Gaba 100 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 this while I'm pregnant or breastfeeding?
The safety data for both L-theanine and GABA during pregnancy and breastfeeding isn't solid enough. The labels advise against it — talk with your doctor or pharmacist about your specific situation to decide what's right for you.
What side effects should I expect?
The most common ones are drowsiness, headaches (from L-theanine), and nausea or stomach upset (from GABA). Some people also report more vivid dreams. These are usually mild, but if you get muscle weakness or a more serious reaction, stop and let your pharmacist know.
Does this actually help with anxiety?
The evidence isn't strong enough yet to say either way. Both ingredients are often marketed for anxiety, but the data we have rates that as insufficient — meaning we don't have solid proof it works for that.
How long can I safely take this?
Both ingredients are generally well tolerated for short-term use, but long-term safety hasn't been well studied. If you're planning to take this for more than a few weeks, ask your pharmacist whether that's a good idea for you.
What is L-theanine and what is GABA?
Both are amino acids your brain naturally makes. L-theanine is in green tea and may support focus. GABA is your brain's main calming messenger. The supplement versions aim to boost these, though how well they work when you swallow them is debated.
Is this safe to use with my other medications?
It depends on what you're taking. Blood pressure meds and sedating drugs are the main concerns. Use the search tool on this page with your exact medication list, or call us — we can tell you in two minutes whether it's safe to combine.

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

Not sure if L-Theanine 200 mg Plus Gaba 100 mg 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 200 mg Plus Gaba 100 mg label
Go deeper

The Full Monographs Behind L-Theanine 200 mg Plus Gaba 100 mg’s Ingredients

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

Herb & supplement monograph

Gamma-aminobutyric Acid (gaba)

Interacts with 419 drugs

GABA is a calming chemical messenger (neurotransmitter) that your body makes on its own, and it is sold as a supplement for stress, anxiety, and sleep. The science behind oral GABA supplemen...

Read the full Gamma-aminobutyric Acid (gaba) monograph → 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 200 mg Plus Gaba 100 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 18 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.

Gamma-aminobutyric Acid (gaba) 12 references
  1. Cavagnini F, Invitti C, Pinto M, et al. Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man. Acta Endocrinol (Copenh) 1980;93:149-54.
  2. Nurnberger JI Jr, Berrettini WH, Simmons-Alling S, et al. Intravenous GABA administration is anxiogenic in man. Psychiatry Res 1986;19:113-7. PubMed
  3. Gershman RN, Vasilenko MA, Iliushina GG, et al. [Gammalon in the rehabilitation in infantile cerebral palsy]. Pediatr.Akus.Ginekol. 1977;(6):26-7.
  4. Loeb C, Benassi E, Bo, GP, et al. Preliminary evaluation of the effect of GABA and phosphatidylserine in epileptic patients. Epilepsy Res. 1987;1:209-12 . PubMed
  5. Inoue K, Shirai T, Ochiai H, et al. Blood-pressure-lowering effect of a novel fermented milk containing gamma-aminobutyric acid (GABA) in mild hypertensives. Eur J Clin Nutr 2003;57:490-95.
  6. ELLIOTT, K. A. and JASPER, H. H. Gammaaminobutyric acid. Physiol Rev. 1959;39(2):383-406.
  7. Winsky-Sommerer, R. Role of GABAA receptors in the physiology and pharmacology of sleep. Eur.J.Neurosci. 2009;29(9):1779-1794.
  8. Meldrum, B. S. GABAergic mechanisms in the pathogenesis and treatment of epilepsy. Br.J.Clin.Pharmacol. 1989;27 Suppl 1:3S-11S. PubMed
  9. Loeb, C., Marinari, U. M., Benassi, E., Besio, G., Cottalasso, D., Cupello, A., Maffini, M., Mainardi, P., Pronzato, M. A., and Scotto, P. A. Phosphatidylserine increases in vivo the synaptosomal uptake of exogenous GABA in rats. Exp.Neurol. 1988;99(2):4 PubMed
  10. Melis, G. B., Paoletti, A. M., Mais, V., and Fioretti, P. Interference of dopamine infusion on gamma-amino butyric acid (GABA)-stimulated prolactin increase. J.Endocrinol.Invest 1980;3(4):445-448.
  11. Boonstra E, de Kleijn R, Colzato LS, Alkemade A, Forstmann BU, Nieuwenhuis S. Neurotransmitters as food supplements: the effects of GABA on brain and behavior. Front Psychol. 2015 Oct 6;6:1520. doi: 10.3389/fpsyg.2015.01520. eCollection 2015. PubMed
  12. de Bie TH, Witkamp RF, Balvers MG, Jongsma MA. Effects of ?-aminobutyric acid supplementation on glucose control in adults with prediabetes: A double-blind, randomized, placebo-controlled trial. Am J Clin Nutr 2023;118(3):708-719. PubMed

See these in context on the Gamma-aminobutyric Acid (gaba) monograph →

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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