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Dietary supplement

L-Theanine 200 mg Ingredients & Drug Interactions

by Protocol For Life Balance

L-Theanine 200 mg label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Theanine 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 Protocol For Life Balance 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.

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Check Your Meds Against L-Theanine 200 mg by Protocol For Life Balance

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

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HelloPharmacist Scorecard of L-Theanine 200 mg by Protocol For Life Balance

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 and inositol. L-theanine is an amino acid that may support cognitive function and relaxation.

Inositol is a carbohydrate compound your body produces naturally; it's used in this formulation for its potential effects on metabolic and ovarian health. The capsule also contains inactive ingredients — hypromellose, stearic acid, and silicon dioxide — which are fillers and binders that help hold the capsule together.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: relaxation, calm mental state, and cognitive support.
  • We looked for evidence on: Anxiety, Generalized anxiety disorder (GAD), Panic disorder, Stress, Insomnia, Cognitive function — and 4 related terms.
  • The strongest evidence on file: Theanine is rated "Possibly Effective" for Cognitive function (Natural Medicines).
  • Also on file: Inositol is rated "Possibly Ineffective" for Acute respiratory distress syndrome (ARDS), Anxiety.
  • Also on file: Inositol is rated "Insufficient Reliable Evidence To Rate" for Insomnia, Panic disorder, Post-traumatic stress disorder (PTSD).

For L-theanine, the evidence shows it is possibly effective for cognitive function. The evidence is insufficient to rate it for age-related cognitive decline, Alzheimer's disease, generalized anxiety, OCD, or cancer.

Inositol shows possibly effective evidence for polycystic ovary syndrome (PCOS), metabolic syndrome, and preterm labor. However, it's rated possibly ineffective for anxiety, diabetic nerve damage, and depression.

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.

Both ingredients are generally well tolerated at common doses. Inositol's most common side effects are mild digestive ones — diarrhea, gas, and nausea.

L-Theanine may cause headaches, drowsiness, or vivid dreams in some people. One case of a facial tic was reported in a child, but it wasn't clearly linked to L-theanine.

For pregnancy: inositol is rated possibly safe, but use only under medical supervision since full safety data doesn't exist. L-Theanine has insufficient safety data in pregnancy, so the data advises against use during pregnancy and while breastfeeding.

Talk with your doctor or pharmacist about whether this product is right for you if you're pregnant or nursing.

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.

Before taking this product, check with your doctor or pharmacist if you take blood pressure medications (antihypertensives) — L-theanine may lower blood pressure further. Also clear it if you take antidiabetes drugs or any blood sugar medications, since inositol can lower glucose levels.

Let them know too if you're on sedatives, sleep aids, or antidepressants, as minor interactions are documented with those drug types.

Check your own medication Run your meds through the checker above

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.

This product may help with cognitive function and certain metabolic conditions, but it interacts with blood pressure and blood sugar medications, as well as with sedatives and some antidepressants. If you take any of those types of drugs, check your specific medications with your doctor or pharmacist before starting.

Avoid it during pregnancy and breastfeeding. It's generally well tolerated otherwise, though digestive upset and drowsiness are possible.

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 Jun 22, 2023.

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 Protocol For Life Balance
Barcode (UPC) 707359101470
Net contents 60 Veg Capsule(s)
Market status On market
Date entered into DSLD Jun 22, 2023
DSLD ID 292265
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, 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 200 mg by Protocol For Life Balance, 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 Veg Capsule(s)
Maximum serving Sizes:
1 Veg Capsule(s)
Servings per container
60
UPC/BARCODE
707359101470
IngredientAmount% DV
Inositol100 mg--
L-Theanine200 mg--

Other ingredients: Hypromellose, Stearic Acid, 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: Take 1 capsule 1 to 2 times daily as needed, or as directing by your healthcare practitioner.

Formula

How it works: Theanine is an amino acid show to be the constituent responsible for the calming properties of green tea. Theanine can cross the blood-brain barrier and enhances healthy alpha brain-wave activity, which is associated with a relaxed, but alert state. At the same time, theanine helps to support the health of brain cells exposed to typical stimulation from excitatory neurotransmitters and promotes normal dopamine and GABA release. Clinical studies have shown that theanine can support relaxation without drowsiness and promote healthy cognitive function.

Precautions

Cautions/interactions: Theanine may interact with chemotherapy agents, psychoactive drugs, and antihypertensive medications. If you are taking any of these medications, consult your healthcare practitioner before taking this product.

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.

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.

Formulation

Natural color variation may occur in this product. Relaxed but alert mental state Cognitive support

Non-GMO

Vegetarian/vegan

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

FDA Statement of Identity

A 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 Protocol For Life Balance 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 Protocol For Life Balance

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

Serving size1 Veg 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: Hypromellose, Stearic Acid, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Theanine 200 mg by Protocol For Life Balance 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
258 Moderate 393 Minor

Ingredients driving the most interactions

L-Theanine 565
Inositol 86

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 Inositol

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

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 200 mg, from the product label.

Protocol For Life Balance

See all Protocol For Life Balance products
Name
Protocol For Life Balance
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
www.protocolforlife.com
Pharmacist Counseling Corner

L-Theanine 200 mg by Protocol For Life Balance: Common Questions

Does L-Theanine 200 mg by Protocol For Life Balance 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 this if I'm on blood pressure medication?
Not without checking first. L-Theanine in this product may lower blood pressure on its own, which could make your medication work too well and drop your pressure too far. Talk to your doctor or pharmacist about your specific blood pressure drug and dose before starting.
What are the most common side effects?
Inositol may cause mild digestive upset — diarrhea, gas, or nausea. L-Theanine might cause headaches, drowsiness, or more vivid dreams. Both are generally well tolerated, and side effects tend to be mild.
Is this safe to take during pregnancy?
Inositol is rated possibly safe in pregnancy, but only under medical supervision — full safety data doesn't exist yet. L-Theanine has not been studied enough in pregnancy, so the data advises against it. Talk with your doctor or pharmacist about what's right for your situation.
Will this help my anxiety?
The evidence for L-Theanine's effect on generalized anxiety is insufficient — we don't have reliable data to say it works. Inositol is actually rated possibly ineffective for anxiety. If you're considering this for that reason, discuss other options with your doctor.
Can I take this with my diabetes medication?
Not without checking first. Inositol can lower blood glucose, so combining it with antidiabetes drugs might raise your risk of low blood sugar. Your doctor or pharmacist needs to review your specific medication and monitor your blood sugar closely if you do take both.
Is L-Theanine the same as L-theanine in tea?
Yes — L-theanine is a naturally occurring amino acid found in tea leaves. This supplement is a concentrated dose of the same compound, so the ingredient and its effects are the same, just in a higher amount per serving.

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

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 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 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

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