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Dietary supplement

Thea-Zen Ingredients & Drug Interactions

by HBC Protocols

Thea-Zen label
See full label image
Capsule Category: Amino Acid/protein
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 Thea-Zen 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

Thea-Zen is a dietary supplement by HBC Protocols 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 Theanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Thea-Zen by HBC Protocols

Ask about any prescription or over-the-counter medication and we check it for interactions with Thea-Zen by HBC Protocols — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Thea-Zen by HBC Protocols

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 Sep 17, 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 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

Thea-Zen contains one active ingredient: theanine, an amino acid that occurs naturally in tea. The capsule also contains several inactive ingredients — vitamin D, vitamin E, cyclodextrin, maltodextrin, and magnesium stearate — which are fillers, binders, and excipients that help hold the capsule together.

Does it work?

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

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

Why this rating?
  • The label markets this product for: relaxation and calm without drowsiness.
  • We looked for evidence on: Generalized anxiety disorder (GAD), Stress, anxiety, mental relaxation.
  • The closest evidence on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Generalized anxiety disorder (GAD) (Natural Medicines).
  • Also on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Stress.

Theanine is possibly effective for cognitive function based on the data we hold. For age-related cognitive decline, Alzheimer's disease, generalized anxiety disorder, obsessive-compulsive disorder, and cancer, the evidence is insufficient to rate — we don't have enough reliable data to tell you whether it works for those uses.

The evidence, ingredient by ingredient 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 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Theanine is generally well tolerated in healthy adults for short-term use, but how safe it is long-term isn't well studied. Some people have reported headaches, drowsiness, longer sleep, or increased dreaming.

One case of a facial tic was reported in a child, though it stopped when theanine was discontinued and the child had a history of tics, so the link was uncertain. There isn't enough safety data for pregnancy or breastfeeding — the guidance is to avoid it during both.

If you're pregnant, planning to become pregnant, or breastfeeding, talk with your doctor or pharmacist before taking this product.

Side effects, ingredient by ingredient 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?
  • 1 of the 1 matched ingredient can interact with medications — 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.

Check your blood pressure medications first — theanine may lower blood pressure and boost their effect. Also double-check any sedatives or sleep aids (CNS depressants) and antidepressants (serotonergic drugs) you take, though the risk with those is smaller.

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.

Thea-Zen may help with cognitive function, but the evidence for other uses isn't established. If you take blood pressure medication, sedatives, or antidepressants, check your exact medications with the tool on this page before starting it.

For any other questions about whether it's right for you — especially if you're pregnant, breastfeeding, or have health conditions — talk with your doctor or pharmacist.

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 Jun 23, 2017.

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 Thea-Zen, straight from the product label.

Brand HBC Protocols
Barcode (UPC) 679840871820
Net contents 240 Capsule(s)
Market status On market
Date entered into DSLD Jun 23, 2017
DSLD ID 74988
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Kosher, Halal
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 Thea-Zen by HBC Protocols, 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 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
240
UPC/BARCODE
679840871820
IngredientAmount% DV
Theanine100 mg--

Other ingredients: Vitamin D, Vitamin E, Cyclodextrin, Maltodextrin, Magnesium Stearate

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 to 2 capsules per day with water or juice on an empty stomach, or as directed by your qualified health consultant.

Because it has a mild taste, capsules may be opened and dissolved in water.

General Statements

L-theanine, a unique free form amino acid found in green tea and various mushrooms, has been shown to increase tranquilizing alpha-waves without inducing drowsiness. Clinical studies have shown it to be effective in single doses of 100 to 200 mg 1 to 3 times daily or as needed depending on stress and anxiety levels. For those seeking a continuous mood eleveating effect, one capsule can be taken four times throughout the day. Based on the results of clinical studies, L-theanine is most effective in the range 50-200 mg, with the effect being felt within 30 minutes and lasting for 8-10 hours. Individuals with high stress levels may increase their dosage of L-theanine to at least 100 mg, with no more than 600 mg being taken in a six hour period. FDA recommends a maximum dose of 1200 mg daily, although the reason for this limit is not clear, due to its demonstrated safety. There are no known adverse reactions to L.theanine and no drug interactions have been reported. L-theanine is not affected by food and may be taken anytime, as needed.

Meditation in a Bottle

Precautions

Although it is probably safe for pregnant women and nursing mothers, we discourage its use by them pending conclusive research.

Caution: L-theanine enhances chemotherapy effects. If you are receiving chemotherapy, check with your doctor.

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.

Formula

Theanine 99.7% Pure (Research grade)

100% Kosher and Halal approved vegetable capsule.

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

See for yourself

Thea-Zen by HBC Protocols label

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

Thea-Zen 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 Thea-Zen by HBC Protocols

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container240 Amounts shown are per serving.

Theanine

Interacts with
565 drugs
100 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...

Theanine monograph & interactions

Other (inactive) ingredients: Vitamin D, Vitamin E, Cyclodextrin, Maltodextrin, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Thea-Zen by HBC Protocols Drug Interactions

Want to check YOUR meds against Thea-Zen?

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

Theanine 565

Individual Drug Interactions

The ingredients in Thea-Zen interact with 565 drugs. Click any drug to see the details.

1 of the 1 ingredient in Thea-Zen interact with drugs. Each result below shows which ingredient is responsible. Theanine

Each ingredient & the kinds of drugs it affects

For each ingredient in Thea-Zen 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.

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
Theanine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Thea-Zen, from the product label.

HBC Protocols

See all HBC Protocols products
Name
HBC Protocols
Street Address
8205 Santa Monica Blvd. Suite 472
City
Los Angeles
State
CA
ZipCode
90046
Phone Number
888.497.3742
Web Address
www.hbcprotocols.com
Pharmacist Counseling Corner

Thea-Zen by HBC Protocols: Common Questions

Does Thea-Zen by HBC Protocols interact with any medications?
Yes. Based on its ingredients, Thea-Zen 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?
Thea-Zen contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
What does theanine do?
Theanine is an amino acid found naturally in tea. It's possibly effective for cognitive function, though the evidence for other uses like anxiety or memory decline in older adults isn't established yet.
Can I take this if I'm pregnant or breastfeeding?
There isn't enough safety data either way. The recommendation is to avoid it during pregnancy and while breastfeeding. Talk with your doctor or pharmacist for personalized advice if you're in either situation.
What side effects might I notice?
Headaches and drowsiness are the most common reports, along with longer or more vivid dreams. It's generally well tolerated for short-term use in healthy people.
How long is it safe to take?
Short-term safety is well established, but we don't have good long-term safety data. If you're thinking about taking it for weeks or months, mention that to your doctor or pharmacist.
Does it interact with my blood pressure medicine?
Possibly — theanine can lower blood pressure on its own, which might strengthen the effect of antihypertensive drugs. Use the interaction checker on this page to look up your specific medication, or ask your pharmacist.

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

Not sure if Thea-Zen is safe with your meds?

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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.

Thea-Zen label
Go deeper

The Full Monographs Behind Thea-Zen’s Ingredients

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

Herb & supplement monograph

Theanine

Interacts with 565 drugs

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong drowsiness. Early research suggests it may...

Read the full Theanine monograph →
Sources

Sources & How We Checked

Thea-Zen'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 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
  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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