L-Theanine 400 mg Ingredients & Drug Interactions
What is this page for?
First and foremost: checking L-Theanine 400 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
L-Theanine 400 mg is a dietary supplement by Mental Refreshment 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.
Check Your Meds Against L-Theanine 400 mg by Mental Refreshment
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Theanine 400 mg by Mental Refreshment — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
Ask the Pharmacist
A licensed pharmacist will answer your question by email — free, usually within 24 hours.
Got it — thank you!
A licensed pharmacist will answer within 24 hours. Keep an eye on your email (worth checking spam, just in case).
HelloPharmacist Scorecard of L-Theanine 400 mg by Mental Refreshment
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.
What’s inside
Full disclosure
This product contains one active ingredient: L-theanine 400 mg per capsule. L-theanine is an amino acid that naturally occurs in tea leaves and is believed to support relaxation and mental focus without causing the jittery feeling associated with caffeine.
The capsules also contain two inactive ingredients — gelatin and rice powder — which serve as the capsule material and filler.
Does it work?
Moderate evidence
The evidence for L-theanine in cognitive function is rated possibly effective, meaning there's some supportive data, though it's not conclusive. For other uses listed — age-related cognitive decline, Alzheimer disease, generalized anxiety disorder, obsessive-compulsive disorder, and cancer — the evidence we hold is insufficient to rate whether it works.
That doesn't mean it doesn't work for those conditions; it means reliable research backing those claims isn't established in our data.
How safe is it?
Well-documented data
L-Theanine is generally well tolerated in healthy adults when used short-term. However, its safety over the long run hasn't been studied thoroughly, so we don't have solid data on extended use.
Common side effects reported include headaches, drowsiness, longer sleep duration, and more vivid dreams. One case of a facial tic was reported in a child taking 400 mg daily, though it resolved when the supplement was stopped — and the child had a history of tics, so the link wasn't clear.
There isn't enough safety data for pregnancy or breastfeeding, so it's best to avoid this product if you're pregnant or nursing. Talk with your doctor or pharmacist for personalized advice if you're in either situation.
Meds to double-check
Moderate interaction found
Before you start, double-check with your doctor or pharmacist if you take blood pressure medications — theanine can lower pressure and might amplify their effect. Also mention this product if you use any sedating drugs (CNS depressants) or serotonin-related medications, though those interactions are less likely to be clinically significant.
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.
L-Theanine may help with focus and calm, and it's generally well tolerated short-term. The biggest concern is using it alongside blood pressure medications — check with your doctor or pharmacist first if you take any.
If you're pregnant or breastfeeding, avoid it until you've had a chance to discuss it 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 Apr 22, 2021.
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
General information
Key facts about L-Theanine 400 mg, straight from the product label.
| Brand | Mental Refreshment |
|---|---|
| Barcode (UPC) | 715854664710 |
| Net contents | 180 Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Apr 22, 2021 |
| DSLD ID | 247845 |
| Product type | Non-nutrient/non-botanical |
| Supplement form | Capsule |
| Dietary claims / uses | All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years), Gluten Free, Dairy Free, Sugar Free |
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 400 mg by Mental Refreshment, sourced from the NIH Dietary Supplement Label Database.
Tap any ingredient to jump to its full detail below.
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.
General Statements
Premium Brand / Optimum Results
100% Satisfaction Guaranteed
Formulation
Maximum strength Boosts cognition and mental performance Supports cardiovascular function Promotes relaxation - Calms the mind
Contains No: Artificial coloring, artificial flavor, preservatives, yeast, corn, milk or milk derivatives, lactose, salt, sodium, soy, sugar, gluten, starch or wheat.
Guaranteed Laboratory Tested Quality
We have assayed & fully guarantee the quality & potency of this product.
FDA Statement of Identity
Dietary Supplement
Precautions
Keep out of reach of children.
Warning: If you are pregnant, nursing or taking any medications, consult your doctor before use.
Discontinue use and consult your doctor if any adverse reactions occur.
Storage
Store in a dry place and avoid excessive heat.
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.
Seals/Symbols
Manufactured in a FDA Registered facility that conforms to GMP standards GMP Good Manufacturing Practice Consistent Quality Made in the USA
Suggested/Recommended/Usage/Directions
Directions: For adults, take two (2) capsules daily before a meal. As a reminder, discuss the supplements and medications you take with your health care providers.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Theanine 400 mg by Mental Refreshment label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in L-Theanine 400 mg by Mental Refreshment
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size2 Capsule(s) Dosage formCapsule Servings per container90 Amounts shown are per serving.
L-Theanine
Interacts with565 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 dro...
L-Theanine monograph & interactionsOther (inactive) ingredients: Gelatin, Rice powder. These complete the product’s ingredient list but are not active constituents.
L-Theanine 400 mg by Mental Refreshment Drug Interactions
HelloPharmacist Interaction Report
L-Theanine 400 mg by Mental Refreshment does interact with certain medications, primarily through its potential to lower blood pressure and affect how your nervous system works.
Read the full breakdown — every affected drug type, severity by severity
The main concern is with blood pressure medications (antihypertensives). Theanine can lower blood pressure on its own, and when combined with drugs that do the same job, the effect may add up — potentially dropping your pressure too far.
This is a Moderate-severity interaction, so if you take any blood pressure medication, this is worth discussing with your doctor or pharmacist before starting.
Theanine may also have Minor interactions with sedating drugs (CNS depressants) — theoretically it could add to drowsiness — and with serotonin-related medications. However, the serotonin concern is largely theoretical; clinical reports of actual serotonin problems from theanine alone are absent.
Altogether, these interactions span 565 individual medications.
Use the search tool below to check your exact medications before you begin.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Theanine 400 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 checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in L-Theanine 400 mg interact with 565 drugs. Click any drug to see the details.
1 of the 1 ingredient in L-Theanine 400 mg interact with drugs. Each result below shows which ingredient is responsible. L-Theanine
AcebutololRhotral, Sectral
How Acebutolol interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Acebutolol interactionAcetazolamideAk-Zol, Diamox
How Acetazolamide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineCns Depressants, Antihypertensive Drugs Moderate
Interaction Summary
Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants.
Read the full L-theanine + Acetazolamide interactionAliskirenTekturna
How Aliskiren interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Aliskiren interactionAmbrisentanLetairis, Volibris
How Ambrisentan interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Ambrisentan interactionAmilorideAmilamont, Midamor
How Amiloride interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amiloride interactionAmiloride, HydrochlorothiazideAmil-Co, Amilzide, Moduret 25, Moduretic
How Amiloride, Hydrochlorothiazide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amiloride, Hydrochlorothiazide interactionAmlodipineNorliqva
How Amlodipine interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine interactionAmlodipine BenzoateKaterzia
How Amlodipine Benzoate interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Benzoate interactionAmlodipine BesilateIstin
How Amlodipine Besilate interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besilate interactionAmlodipine BesylateNorvasc
How Amlodipine Besylate interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besylate interactionAmlodipine Besylate, BenazeprilLotrel
How Amlodipine Besylate, Benazepril interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besylate, Benazepril interactionAmlodipine, CelecoxibConsensi
How Amlodipine, Celecoxib interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine, Celecoxib interactionAmmonium ChlorideAmmonium Chloride
How Ammonium Chloride interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Ammonium Chloride interactionAprocitentanTryvio
How Aprocitentan interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Aprocitentan interactionAtenololAtenix, Tenormin
How Atenolol interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol interactionAtenolol, ChlortalidoneAtenixCo, Tenoret 50, Totaretic
How Atenolol, Chlortalidone interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol, Chlortalidone interactionAtenolol, ChlorthalidoneTenoretic
How Atenolol, Chlorthalidone interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol, Chlorthalidone interactionAzilsartanEdarbi
How Azilsartan interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Azilsartan interactionAzilsartan, ChlorthalidoneEdarbyclor
How Azilsartan, Chlorthalidone interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Azilsartan, Chlorthalidone interactionBenazeprilLotensin
How Benazepril interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benazepril interactionBenazepril, HydrochlorothiazideLotensin HCT
How Benazepril, Hydrochlorothiazide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benazepril, Hydrochlorothiazide interactionBendroflumethiazideAprinox, Naturetin, Neo-NaClex
How Bendroflumethiazide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide interactionBendroflumethiazide, NadololCorzide
How Bendroflumethiazide, Nadolol interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide, Nadolol interactionBendroflumethiazide, Rauwolfia SerpentinaRauzide
How Bendroflumethiazide, Rauwolfia Serpentina interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide, Rauwolfia Serpentina interactionBenzthiazideExna
How Benzthiazide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benzthiazide interactionBetaxololBetoptic, Kerlone
How Betaxolol interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Betaxolol interactionBisoprololZebeta
How Bisoprolol interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bisoprolol interactionBisoprolol, HydrochlorothiazideZiac
How Bisoprolol, Hydrochlorothiazide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bisoprolol, Hydrochlorothiazide interactionBosentanTracleer
How Bosentan interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bosentan interactionBumetanideBurinex
How Bumetanide interacts with L-Theanine 400 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bumetanide interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Theanine 400 mg 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
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.
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.
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.
Brand information
Manufacturer and brand details for L-Theanine 400 mg, from the product label.
L-Theanine 400 mg by Mental Refreshment: Common Questions
Does L-Theanine 400 mg by Mental Refreshment interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
What is L-theanine supposed to do?
What are the side effects?
Is it safe to take long-term?
Can I take this while pregnant or breastfeeding?
What are the inactive ingredients?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Theanine 400 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
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.
The Full Monographs Behind L-Theanine 400 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
L-Theanine 400 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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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
- Yokogoshi H, Kobayashi M. Hypotensive effect of gamma-glutamylethylamide in spontaneously hypertensive rats. Life Sci 1998;62:1065-8.
- 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
- 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
- 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-
- 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.
- 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
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