Interactions on record — worth a quick check against your medications. Check your meds →
Dietary supplement

L-Theanine Extra Strength Ingredients & Drug Interactions

by BRI Nutrition

L-Theanine Extra Strength label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Oct 7, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Theanine Extra Strength 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 Extra Strength is a dietary supplement by BRI Nutrition with 2 active ingredients. Its ingredients are commonly taken for polycystic ovary syndrome (pcos), anxiety and panic, depression and mood.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, Inositol. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against L-Theanine Extra Strength by BRI Nutrition

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

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of L-Theanine Extra Strength by BRI Nutrition

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 Oct 8, 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 capsule contains two active ingredients: inositol and L-theanine. Inositol is the ingredient studied most often for conditions such as polycystic ovary syndrome and metabolic syndrome.

L-theanine is the namesake ingredient, and it has mainly been studied for cognitive function. The product also lists four inactive ingredients: rice flour, cellulose, magnesium stearate, and silicon dioxide.

These are fillers and processing agents, not active ingredients.

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 and cardiovascular function support.
  • We looked for evidence on: Anxiety, Generalized anxiety disorder (GAD), Panic disorder, Stress, Hypertension, Cardiovascular disease — and 3 related terms.
  • The closest evidence on file: Inositol is rated "Possibly Ineffective" for Acute respiratory distress syndrome (ARDS) (Natural Medicines).
  • Also on file: Inositol is rated "Possibly Ineffective" for Anxiety.
  • Also on file: Inositol is rated "Insufficient Reliable Evidence To Rate" for Pregnancy-induced hypertension, Panic disorder, Post-traumatic stress disorder (PTSD).

For inositol, the evidence is rated Possibly Effective for polycystic ovary syndrome (PCOS), metabolic syndrome, and preterm labor. It is rated Possibly Ineffective for anxiety, diabetic neuropathy, and depression.

For L-theanine, cognitive function is rated Possibly Effective. Age-related cognitive decline, Alzheimer disease, generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), and attention deficit-hyperactivity disorder (ADHD) have insufficient reliable evidence to rate.

The evidence, ingredient by ingredient Inositol 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.

Inositol is generally well tolerated at common doses, with mostly mild digestive side effects such as diarrhea, gas, and nausea. Cold and allergy symptoms have been reported in children taking it with omega-3 fatty acids in clinical research.

One case report described mania in an adult who drank several energy drinks containing inositol, caffeine, and taurine, but it is not known which ingredient was responsible. L-theanine is generally well tolerated in healthy adults for short-term use, but long-term safety is not well studied.

It may cause headaches, drowsiness, longer sleep, and more vivid dreams. Our safety notes advise avoiding it during pregnancy and breastfeeding because safety data is limited.

For inositol, pregnancy is rated Possibly Safe, but its safety note says to use it only under medical supervision. No lactation data is on file for inositol.

Please talk with your own doctor or pharmacist before using either ingredient during pregnancy or breastfeeding.

Side effects, ingredient by ingredient Inositol 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 — Inositol, Theanine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: diabetes medications.
  • 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 with your own doctor or pharmacist before taking this product if you use antidiabetes drugs (Moderate, due to inositol) or antihypertensive drugs (Moderate, due to L-theanine). Also review CNS depressants (Minor) and serotonergic drugs (Minor) with them.

Use the search tool on this page to look up your exact medications.

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.

This product may suit adults looking for a supplement with inositol or L-theanine, and who have discussed it with their own healthcare provider. People who take diabetes medicines, blood pressure medicines, or sedating or mood-related drugs should be especially careful.

Anyone who is pregnant, breastfeeding, or considering it for a child should talk it over with their own doctor or pharmacist first.

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 Mar 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 Extra Strength, straight from the product label.

Brand BRI Nutrition
Barcode (UPC) X000RTQAEP
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Mar 25, 2025
DSLD ID 326531
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
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 Extra Strength by BRI Nutrition, 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:
1 Vegetable Capsule(s)
Maximum serving Sizes:
1 Vegetable Capsule(s)
Servings per container
60
UPC/BARCODE
X000RTQAEP
IngredientAmount% DV
Inositol100 mg--
L-Theanine200 mg--

Other ingredients: Rice Flour, Cellulose, Magnesium Stearate, 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: As a dietary supplement, take 1 capsule 1 to 2 times daily as needed, preferably on an empty stomach.

Formula

Potent: This product has twice the L-Theanine (200 mg per capsules) as in our regular strength product (100 mg per capsule) and is enhanced with 100 mg of Inositol. What it is: L-Theanine is an amino acid naturally found in green tea. L-Theanine promotes relaxation without the drowsiness or negative side effects associated with other calming agents. L-Theanine also supports healthy cardiovascular function through this relaxing effect. This formulation also includes Inositol, a member of the B-Vitamin family that is essential for brain and nervous system health.

Formulation

Quality Value Service Purity Pure & natural

Supports cardiovascular function Supports & promotes relaxation Double strength

Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish or tree nut ingredients.

100% satisfaction guarantee

FDA Statement of Identity

Dietary Supplement

Precautions

Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish or tree nut ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

Storage

Store in a cool, dry place after opening.

General Statements

Please recycle.

FDA Disclaimer Statement

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

Seals/Symbols

Sourced from a GMP Certified Facility Good Manufacturing Practice Quality Assured Made in USA

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

See for yourself

L-Theanine Extra Strength by BRI Nutrition label

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

L-Theanine Extra Strength 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 Extra Strength by BRI Nutrition

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

Serving size1 Vegetable Capsule(s) Dosage formCapsule Servings per container60 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.

Inositol

Interacts with
86 drugs
100 mg per serving

Inositol is a sugar alcohol made naturally in the body and found in many foods, and it is sold as a supplement (often myo-inositol) mainly for PCOS, m...

Inositol monograph & 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

Other (inactive) ingredients: Rice Flour, Cellulose, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Theanine Extra Strength by BRI Nutrition Drug Interactions

Want to check YOUR meds against L-Theanine Extra Strength?

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
258 Moderate 393 Minor

Ingredients driving the most interactions

L-Theanine 565
Inositol 86

Individual Drug Interactions

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

2 of the 2 ingredients in L-Theanine Extra Strength interact with drugs. Each result below shows which ingredient is responsible. L-Theanine Inositol

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Theanine Extra Strength 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

Inositol1 drug type · 86 drugs

Antidiabetes Drugs

Theoretically, taking inositol with antidiabetes drugs might increase the risk of hypoglycemia.
Clinical research shows that inositol lowers blood glucose levels and glycated hemoglobin (HbA1c) levels in patients with diabetes.

Likelihood Possible Evidence A
Inositol full monograph & interactions
The maker

Brand information

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

BRI Nutrition

See all BRI Nutrition products
Name
BRI Nutrition LLC
Street Address
1460 Broadway
City
New York
State
NY
ZipCode
10036
Web Address
www.brinutrition.com
Pharmacist Counseling Corner

L-Theanine Extra Strength by BRI Nutrition: Common Questions

Does L-Theanine Extra Strength by BRI Nutrition interact with any medications?
Yes. Based on its ingredients, L-Theanine Extra Strength 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 Extra Strength 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.
Is this product safe to use during pregnancy?
Inositol is rated Possibly Safe in pregnancy, but its safety note says to use it only under medical supervision. For L-theanine, our safety notes advise avoiding it during pregnancy because there is not enough safety data. Please talk with your own doctor or pharmacist for advice that fits your situation.
What are the most common side effects of L-theanine?
L-theanine may cause headaches, and some people have reported drowsiness, longer sleep, and more vivid dreams. These effects are generally mild, but long-term safety is not well studied.
Does inositol work for anxiety?
Inositol is rated Possibly Ineffective for anxiety in the evidence we hold. Its strongest ratings are for polycystic ovary syndrome (PCOS) and metabolic syndrome, both Possibly Effective.
Does L-theanine help with anxiety or ADHD?
There is insufficient reliable evidence to rate L-theanine for generalized anxiety disorder (GAD) or attention deficit-hyperactivity disorder (ADHD). Its only Possibly Effective rating is for cognitive function.

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

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

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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 Extra Strength label
Go deeper

The Full Monographs Behind L-Theanine Extra Strength’s Ingredients

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

Herb & supplement monograph

Inositol

Interacts with 86 drugs

Inositol is a sugar alcohol made naturally in the body and found in many foods, and it is sold as a supplement (often myo-inositol) mainly for PCOS, mood, and metabolic concerns. The stronge...

Read the full Inositol 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 Extra Strength'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 20 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.

Inositol 14 references
  1. Palatnik A, Frolov K, Fux M, Benjamin J. Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol 2001;21:335-9.. PubMed
  2. Allan SJ, Kavanagh GM, Herd RM, Savin JA. The effect of inositol supplements on the psoriasis of patients taking lithium: a randomized, placebo-controlled trial. Br J Dermatol 2004;150:966-9. PubMed
  3. Machado-Vieira R, Viale CI, Kapczinski F. Mania associated with an energy drink: the possible role of caffeine, taurine, and inositol. Can J Psychiatry 2001;46:454-5. PubMed
  4. Kamenov Z, Kolarov G, Gateva A, Carlomagno G, Genazzani AD. Ovulation induction with myo-inositol alone and in combination with clomiphene citrate in polycystic ovarian syndrome patients with insulin resistance. Gynecol Endocrinol 2015;31(2):131-5. PubMed
  5. Matarrelli B, Vitacolonna E, D'Angelo M, et al. Effect of dietary myo-inositol supplementation in pregnancy on the incidence of maternal gestational diabetes mellitus and fetal outcomes: a randomized controlled trial. J Matern Fetal Neonatal Med 2013;26(1 PubMed
  6. Mukai T, Kishi T, Matsuda Y, Iwata N. A meta-analysis of inositol for depression and anxiety disorders. Hum Psychopharmacol 2014;29(1):55-63. PubMed
  7. Farren M, Daly N, McKeating A, Kinsley B, Turner MJ, Daly S. The Prevention of Gestational Diabetes Mellitus With Antenatal Oral Inositol Supplementation: A Randomized Controlled Trial. Diabetes Care. 2017;40(6):759-63. PubMed
  8. Zheng X, Liu Z, Zhang Y, et al. Relationship Between Myo-Inositol Supplementary and Gestational Diabetes Mellitus: A Meta-Analysis. Medicine (Baltimore). 2015;94(42):e1604. PubMed
  9. Crawford TJ, Crowther CA, Alsweiler J, Brown J. Antenatal dietary supplementation with myo-inositol in women during pregnancy for preventing gestational diabetes. Cochrane Database Syst Rev. 2015;(12):CD011507. PubMed
  10. Maurizi AR, Menduni M, Del Toro R, et al. A pilot study of D-chiro-inositol plus folic acid in overweight patients with type 1 diabetes. Acta Diabetol. 2017;54(4):361-65. PubMed
  11. Leppink EW, Redden SA, Grant JE. A double-blind, placebo-controlled study of inositol in trichotillomania. Int Clin Psychopharmacol. 2017;32(2):107-14. PubMed
  12. Lam S, Mandrekar SJ, Gesthalter Y. A Randomized Phase IIb Trial of myo-Inositol in Smokers with Bronchial Dysplasia. Cancer Prev Res (Phila). 2016;9(12):906-14.
  13. Wozniak J, Faraone SV, Chan J, et al. A randomized clinical trial of high eicosapentaenoic acid omega-3 fatty acids and inositol as monotherapy and in combination in the treatment of pediatric bipolar spectrum disorders: a pilot study. J Clin Psychiatry. PubMed
  14. Vitale SG, Corrado F, Caruso S, et al. Myo-inositol supplementation to prevent gestational diabetes in overweight non-obese women: bioelectrical impedance analysis, metabolic aspects, obstetric and neonatal outcomes - a randomized and open-label, placebo-

See these in context on the Inositol 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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team