L-Theanine 250 mg Ingredients & Drug Interactions
by Kirkman
What is this page for?
First and foremost: checking L-Theanine 250 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.
Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy
L-Theanine 250 mg is a dietary supplement by Kirkman with 1 active ingredient. Its ingredients are commonly taken for anxiety and stress, relaxation and calm, sleep support.Based on those ingredients, 565 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Theanine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Theanine 250 mg by Kirkman
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Theanine 250 mg by Kirkman — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of L-Theanine 250 mg by Kirkman
Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.
What’s inside
Full disclosure
This product contains a single active ingredient: L-theanine 250 mg per capsule. L-theanine is an amino acid found in tea that works in your brain to support relaxation and mental focus.
The capsule also contains inactive ingredients — microcrystalline cellulose, hypromellose, water, and magnesium stearate — which are fillers and binders that hold the capsule together.
Does it work?
Moderate evidence
L-theanine is possibly effective for cognitive function based on available evidence. For age-related cognitive decline, Alzheimer disease, generalized anxiety disorder, obsessive-compulsive disorder, and cancer, the evidence we hold is insufficient to say whether it works or not.
How safe is it?
Well-documented data
L-theanine is generally well tolerated in healthy adults for short-term use, but we don't have good long-term safety data. Some people report headaches, drowsiness, longer sleep, or more vivid dreams.
There isn't enough safety data to know whether it's okay during pregnancy or while breastfeeding — talk with your doctor or pharmacist for personalized guidance if you're pregnant, planning pregnancy, or nursing.
Meds to double-check
Moderate interaction found
Check your blood pressure medications (antihypertensives) before starting — theanine may lower blood pressure further. Also confirm any sedating drugs (sleep aids, anti-anxiety meds) and serotonergic antidepressants with your doctor or pharmacist, since minor additive effects are possible.
The bottom line
Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.
L-theanine may help with focus and mental clarity, but the evidence is strongest for cognitive function and weaker for anxiety or neurological conditions. If you take blood pressure medication, sedatives, or serotonergic drugs like certain antidepressants, check with your doctor or pharmacist first — theanine could affect how those work.
For short-term use in otherwise healthy adults, it's generally tolerated well.
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 Sep 25, 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
General information
Key facts about L-Theanine 250 mg, straight from the product label.
| Brand | Kirkman |
|---|---|
| Barcode (UPC) | 812325022144 |
| Net contents | 100 Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Sep 25, 2023 |
| DSLD ID | 297055 |
| Product type | Non-nutrient/non-botanical |
| Supplement form | Capsule |
| Dietary claims / uses | All Other |
| Intended target group(s) | Adult (18 - 50 Years), Gluten Free, Dairy Free |
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.
Supplement Facts
The label details for L-Theanine 250 mg by Kirkman, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Theanine | 250 mg | -- |
Other ingredients: Microcrystalline Cellulose, Hypromellose, Water, Magnesium Stearate
Tap any ingredient to jump to its full detail below.
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Storage
Important: Store in a cool dry place and tightly capped.
Precautions
Keep out of the reach of children.
Formulation
Free of: Milk, Eggs, Fish, Shellfish, Tree Nuts, Peanuts, Wheat or Soy
Hypoallergenic
Gluten-Free
Seals/Symbols
Ultra Tested cGMP Certified
FDA Statement of Identity
Dietary Supplement
Suggested/Recommended/Usage/Directions
Suggested Use: Take one to two capsules daily or as directed by a physician.
General Statements
503.694.1600
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Theanine 250 mg by Kirkman label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.
View the full label (PDF)The Ingredients in L-Theanine 250 mg by Kirkman
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 container100 Amounts shown are per serving.
L-Theanine
Interacts with565 drugs
Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong dro...
L-Theanine monograph & interactionsOther (inactive) ingredients: Microcrystalline Cellulose, Hypromellose, Water, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.
L-Theanine 250 mg by Kirkman Drug Interactions
HelloPharmacist Interaction Report
Kirkman's L-Theanine 250 mg interacts with three medication types through its single active ingredient.
The most serious concern is with blood pressure medications (antihypertensives): theanine may lower blood pressure on its own, and combined use could strengthen that effect beyond what you'd expect from the medication alone.
Read the full breakdown — every affected drug type, severity by severity
Theanine also carries minor interactions with sedating drugs (CNS depressants) — theoretically it could add to their drowsiness effect, though whether this matters in real life isn't clear. Similarly, there's a minor theoretical concern with serotonergic drugs (like certain antidepressants), but clinical evidence of actual serotonin-related problems from theanine alone has not been reported.
Altogether, these interactions span 565 individual medications. Before you start this product, run your exact blood pressure medications, sleep aids, and any antidepressants through the interaction checker on this page.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Theanine 250 mg?
Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.
Go to the checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in L-Theanine 250 mg interact with 565 drugs. Click any drug to see the details.
1 of the 1 ingredient in L-Theanine 250 mg interact with drugs. Each result below shows which ingredient is responsible. L-Theanine
AcebutololRhotral, Sectral
How Acebutolol interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Acebutolol interactionAcetazolamideAk-Zol, Diamox
How Acetazolamide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineCns Depressants, Antihypertensive Drugs Moderate
Interaction Summary
Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants.
Read the full L-theanine + Acetazolamide interactionAliskirenTekturna
How Aliskiren interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Aliskiren interactionAmbrisentanLetairis, Volibris
How Ambrisentan interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Ambrisentan interactionAmilorideAmilamont, Midamor
How Amiloride interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amiloride interactionAmiloride, HydrochlorothiazideAmil-Co, Amilzide, Moduret 25, Moduretic
How Amiloride, Hydrochlorothiazide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amiloride, Hydrochlorothiazide interactionAmlodipineNorliqva
How Amlodipine interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine interactionAmlodipine BenzoateKaterzia
How Amlodipine Benzoate interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Benzoate interactionAmlodipine BesilateIstin
How Amlodipine Besilate interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besilate interactionAmlodipine BesylateNorvasc
How Amlodipine Besylate interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besylate interactionAmlodipine Besylate, BenazeprilLotrel
How Amlodipine Besylate, Benazepril interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine Besylate, Benazepril interactionAmlodipine, CelecoxibConsensi
How Amlodipine, Celecoxib interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Amlodipine, Celecoxib interactionAmmonium ChlorideAmmonium Chloride
How Ammonium Chloride interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Ammonium Chloride interactionAprocitentanTryvio
How Aprocitentan interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Aprocitentan interactionAtenololAtenix, Tenormin
How Atenolol interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol interactionAtenolol, ChlortalidoneAtenixCo, Tenoret 50, Totaretic
How Atenolol, Chlortalidone interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol, Chlortalidone interactionAtenolol, ChlorthalidoneTenoretic
How Atenolol, Chlorthalidone interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Atenolol, Chlorthalidone interactionAzilsartanEdarbi
How Azilsartan interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Azilsartan interactionAzilsartan, ChlorthalidoneEdarbyclor
How Azilsartan, Chlorthalidone interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Azilsartan, Chlorthalidone interactionBenazeprilLotensin
How Benazepril interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benazepril interactionBenazepril, HydrochlorothiazideLotensin HCT
How Benazepril, Hydrochlorothiazide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benazepril, Hydrochlorothiazide interactionBendroflumethiazideAprinox, Naturetin, Neo-NaClex
How Bendroflumethiazide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide interactionBendroflumethiazide, NadololCorzide
How Bendroflumethiazide, Nadolol interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide, Nadolol interactionBendroflumethiazide, Rauwolfia SerpentinaRauzide
How Bendroflumethiazide, Rauwolfia Serpentina interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bendroflumethiazide, Rauwolfia Serpentina interactionBenzthiazideExna
How Benzthiazide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Benzthiazide interactionBetaxololBetoptic, Kerlone
How Betaxolol interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Betaxolol interactionBisoprololZebeta
How Bisoprolol interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bisoprolol interactionBisoprolol, HydrochlorothiazideZiac
How Bisoprolol, Hydrochlorothiazide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bisoprolol, Hydrochlorothiazide interactionBosentanTracleer
How Bosentan interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bosentan interactionBumetanideBurinex
How Bumetanide interacts with L-Theanine 250 mg — through 1 ingredient. Tap an ingredient for the detail:
L-theanineAntihypertensive Drugs Moderate
Interaction Summary
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Read the full L-theanine + Bumetanide interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Theanine 250 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.
L-Theanine
Antihypertensive Drugs
Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Animal research shows that theanine can lower blood pressure in spontaneously hypertensive animals. Theoretically, concomitant use of theanine and antihypertensive drugs might potentiate the antihypertensive activity.
Cns Depressants
Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Theoretically, theanine may compete with glutamate and/or increase plasma gamma-aminobutyric acid (GABA) levels, which could cause CNS depression. In one clinical study, some subjects taking oral theanine reported drowsiness.
Serotonergic Drugs
Clinical studies regarding the effects of L-theanine on serotonin levels are conflicting. Some studies suggest it can increase serotonin levels in the brain while others report that it may decrease them. Nevertheless, there have been no reports of l-theanine being a causative agent in serotonergic-related side effects or serotonin syndrome.
Brand information
Manufacturer and brand details for L-Theanine 250 mg, from the product label.
Kirkman
See all Kirkman products- Name
- Kirkman
- City
- Lake Oswego
- State
- OR
- ZipCode
- 97035
- Phone Number
- (800) 245-8282
- Web Address
- www.kirkmangroup.com
L-Theanine 250 mg by Kirkman: Common Questions
Does L-Theanine 250 mg by Kirkman interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
What is L-theanine, and what's it supposed to do?
Can I take this if I'm pregnant or breastfeeding?
What side effects might I notice?
Is this safe for long-term use?
Will this interact with my blood pressure medication?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Theanine 250 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.
The Full Monographs Behind L-Theanine 250 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
L-Theanine 250 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.
The 6 references behind this product’s interaction data
Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.
Theanine 6 references
- Yokogoshi H, Kobayashi M. Hypotensive effect of gamma-glutamylethylamide in spontaneously hypertensive rats. Life Sci 1998;62:1065-8.
- Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., and Scholey, A. B. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol.Psychol. 2008;77(2):113-122. PubMed
- Yokogoshi, H., Kato, Y., Sagesaka, Y. M., Takihara-Matsuura, T., Kakuda, T., and Takeuchi, N. Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci.Biotechnol.Biochem. 1995;59(4):615-618. PubMed
- Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011;16(4):348-
- Hidese S, Ota M, Wakabayashi C, et al. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr 2017;29(2):72-9.
- Tsuchiya T, Honda H, Oikawa M, et al. Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients. Int J Clin Oncol 2016;21(6):1085-90. PubMed
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC