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Dietary supplement

200 mg of Zen Ingredients & Drug Interactions

by Allergy Research Group

200 mg of Zen 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 200 mg of 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

200 mg of Zen is a dietary supplement by Allergy Research Group with 2 active ingredients. 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, GABA. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against 200 mg of Zen by Allergy Research Group

Ask about any prescription or over-the-counter medication and we check it for interactions with 200 mg of Zen by Allergy Research Group — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of 200 mg of Zen by Allergy Research Group

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

200 mg of Zen contains two active ingredients: L-theanine and GABA. L-theanine is an amino acid that may help with cognitive function, though evidence for anxiety or age-related cognitive decline is still being studied.

GABA is a neurotransmitter that the body naturally produces; as a supplement, its effectiveness for anxiety, ADHD, athletic performance, and other conditions is not well established. Both are intended to support relaxation and mental clarity, though the science behind supplemental GABA absorption is unclear.

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: Calmness and relaxation support.
  • We looked for evidence on: Anxiety, Generalized anxiety disorder (GAD), Insomnia, Stress, Psychological well-being, Sleep quality — and 1 related terms.
  • The closest evidence on file: Gamma-aminobutyric Acid (gaba) is rated "Insufficient Reliable Evidence To Rate" for Anxiety (Natural Medicines).
  • Also on file: Gamma-aminobutyric Acid (gaba) is rated "Insufficient Reliable Evidence To Rate" for Insomnia, Post-traumatic stress disorder (PTSD), Psychological well-being.
  • Also on file: Theanine is rated "Insufficient Reliable Evidence To Rate" for Generalized anxiety disorder (GAD), Insomnia, Stress.

L-theanine is possibly effective for cognitive function, but the evidence for using it in age-related cognitive decline, Alzheimer disease, generalized anxiety, or obsessive-compulsive disorder is insufficient—we don't have enough reliable data to say it works for those. GABA's effectiveness is insufficient for all the conditions listed in our data: anxiety, ADHD, athletic performance, chronic bronchitis, and cerebral palsy.

In short, if you're taking this for anxiety or cognitive support, the evidence backing those uses is limited.

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

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 L-theanine and GABA are generally well tolerated for short-term use in healthy adults, but long-term safety hasn't been well studied. L-theanine may cause headaches, drowsiness, increased sleep, or increased dreaming in some people.

GABA may cause drowsiness, stomach upset, minor throat burning, muscle weakness, or nausea, though a complete safety evaluation hasn't been done. For pregnancy: there isn't enough safety data for either ingredient, so it's best to avoid this supplement during pregnancy.

For breastfeeding: the same applies—not enough data, so it's best to avoid unless your doctor advises otherwise.

Side effects, ingredient by ingredient Theanine Gamma-aminobutyric Acid (gaba)

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 2 of the 2 matched ingredients can interact with medications — Gamma-aminobutyric Acid (gaba), Theanine.
  • The most serious interaction on file is rated Moderate.
  • For scale: 565 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with us before taking this product if you're on blood pressure medications (antihypertensive drugs)—L-theanine and GABA may lower your pressure further. Also double-check if you take any sedating or CNS-depressant medications, like sleep aids, anti-anxiety drugs, or certain pain relievers.

And if you're on antidepressants or serotonergic drugs, L-theanine warrants a quick review, though serotonin syndrome hasn't been reported with it.

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.

If you take blood pressure medications or sedating drugs, talk to your pharmacist before starting this product—the interaction risk is real. The evidence that it actually works for anxiety or brain function is thin.

If you're generally healthy and not on medications, it's been reasonably tolerated short-term, but we don't know much about long-term safety.

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 Oct 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

At a glance

General information

Key facts about 200 mg of Zen, straight from the product label.

Brand Allergy Research Group
Barcode (UPC) 713947766501
Net contents 120 Vegetarian Capsule(s)
Market status On market
Date entered into DSLD Oct 22, 2021
DSLD ID 257949
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for 200 mg of Zen by Allergy Research Group, 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
60
UPC/BARCODE
713947766501
IngredientAmount% DV
L-Theanine200 mg--
GABA550 mg--

Other ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Rice hull concentrate, Gum Arabic, Sunflower Oil

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.
Formula

200 mg of Zen contains a combination of L-theanine and GABA. L-theanine is found in green tea (Camellia sinensis).

Suggested/Recommended/Usage/Directions

Suggested Use As a dietary supplement, 1 or 2 capsules daily between meals, or as directed by a healthcare practitioner.

Precautions

Warning: If taking antidepressants or other psychotropic medications, use only under the supervision of a qualified healthcare practitioner.

Although we are not aware of any interactions, because these also affect brain function there is theoretical potential for negative or positive interactions, either of which would need to be monitored.

Storage

Keep in cool, dry place, tightly capped.

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.

Formulation

Calmness Support Day or Night

Hypoallergenic

FDA Statement of Identity

Dietary Supplement

Brand IP Statement(s)

Suntheanine

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

See for yourself

200 mg of Zen by Allergy Research Group label

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

200 mg of 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 200 mg of Zen by Allergy Research Group

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

Serving size1 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.

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

GABA

Interacts with
419 drugs
550 mg per serving

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

GABA monograph & interactions

Other (inactive) ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Rice hull concentrate, Gum Arabic, Sunflower Oil. These complete the product’s ingredient list but are not active constituents.

Interaction report

200 mg of Zen by Allergy Research Group Drug Interactions

Want to check YOUR meds against 200 mg of 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

L-Theanine 565
GABA 419

Individual Drug Interactions

The ingredients in 200 mg of Zen interact with 565 drugs. Click any drug to see the details.

2 of the 2 ingredients in 200 mg of Zen interact with drugs. Each result below shows which ingredient is responsible. L-Theanine GABA

Each ingredient & the kinds of drugs it affects

For each ingredient in 200 mg of Zen 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

GABA2 drug types · 419 drugs

Antihypertensive Drugs

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

Likelihood Possible Evidence B
Cns Depressants

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

Likelihood Unlikely Evidence D
GABA full monograph & interactions
The maker

Brand information

Manufacturer and brand details for 200 mg of Zen, from the product label.

Allergy Research Group

See all Allergy Research Group products
Name
Allergy Research Group
City
South Salt Lake
State
UT
ZipCode
84115
Phone Number
800-545-9960
Web Address
www.allergyresearchgroup.com
Pharmacist Counseling Corner

200 mg of Zen by Allergy Research Group: Common Questions

Does 200 mg of Zen by Allergy Research Group interact with any medications?
Yes. Based on its ingredients, 200 mg of 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?
200 mg of Zen 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. Both ingredients in this product may lower blood pressure, so adding them to blood pressure medication could drop your pressure too much. Talk to your pharmacist about your specific medications before you start.
What side effects might I experience?
L-theanine may cause headaches, drowsiness, more vivid dreams, or longer sleep. GABA might cause drowsiness, stomach upset, nausea, throat burning, or muscle weakness. Both can make you tired, especially if you're also taking sedating medications.
Is this safe during pregnancy or breastfeeding?
There isn't enough safety data for either L-theanine or GABA during pregnancy or breastfeeding, so it's best to avoid this supplement unless your doctor advises otherwise. Talk to your doctor or pharmacist if you're expecting or nursing.
Does this actually help with anxiety?
The evidence isn't strong enough yet. For both L-theanine and GABA, the research on anxiety is insufficient—we don't have reliable data showing they work for that purpose. If anxiety is your main reason, talk to your doctor about proven options.
Is L-theanine the same as the amino acid in green tea?
Yes, L-theanine is a naturally occurring amino acid found in green tea, but this supplement contains it isolated and in a higher dose (200 mg combined with GABA). The effects and interactions may differ from drinking tea.
How long has this been studied for safety?
Neither L-theanine nor GABA has been well studied for long-term safety. Both are generally well tolerated in the short term, but we don't know what happens with extended use.

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.

200 mg of Zen label
Go deeper

The Full Monographs Behind 200 mg of 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 → Herb & supplement monograph

Gamma-aminobutyric Acid (gaba)

Interacts with 419 drugs

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

Read the full Gamma-aminobutyric Acid (gaba) monograph →
Sources

Sources & How We Checked

200 mg of 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 18 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

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 →

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

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

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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