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Dietary supplement

L-Theanine 100 mg Ingredients & Drug Interactions

by Exchange Select

L-Theanine 100 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 100 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 100 mg is a dietary supplement by Exchange Select 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.

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Check Your Meds Against L-Theanine 100 mg by Exchange Select

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Theanine 100 mg by Exchange Select — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Theanine 100 mg by Exchange Select

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

Exchange Select's L-Theanine is a straightforward single-ingredient supplement: one 100 mg capsule of L-Theanine, an amino acid found naturally in tea leaves. It's a capsule form, so it also contains inactive ingredients like gelatin, silicon dioxide, magnesium stearate, and a few others that help hold it together and make it easier to swallow.

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: supports relaxation health.
  • We looked for evidence on: Stress, Generalized anxiety disorder (GAD), Insomnia, anxiety, calm.
  • 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 Insomnia, Stress.

The evidence is mixed. L-Theanine is possibly effective for supporting cognitive function — that's the strongest rating we have.

For age-related cognitive decline, Alzheimer's disease, anxiety disorders like GAD and OCD, and cancer, the evidence isn't established enough for us to rate it one way or the other. If you're thinking about L-Theanine for one of those uses, talk it over with your doctor to see if it fits your situation.

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.

L-Theanine is generally well tolerated by healthy adults for short-term use, but we don't have solid data on what happens if you take it long-term. The most common side effects are headaches, drowsiness, longer sleep, and more vivid dreams.

There's not enough safety data to know whether it's okay during pregnancy or while breastfeeding, so the safety data advises against use in both cases — talk with your doctor or pharmacist for personalized guidance if you're pregnant, planning to become pregnant, or nursing.

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 (antihypertensives) and any central nervous system depressants (sedatives, sleep aids, certain pain medications) with your doctor or pharmacist before adding L-Theanine. Also flag any serotonergic drugs (like antidepressants) so your healthcare provider can weigh the conflicting evidence and confirm it's safe for you.

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.

L-Theanine may be worth considering if you're interested in cognitive support and you don't take blood pressure medications or CNS depressants. If you do take those or any other prescriptions, check them against this product first with your doctor or pharmacist.

Long-term safety hasn't been well studied, so short-term use is what we know most about.

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 Aug 22, 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 L-Theanine 100 mg, straight from the product label.

Brand Exchange Select
Barcode (UPC) 614299038400
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Aug 22, 2017
DSLD ID 76815
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free
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 100 mg by Exchange Select, 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:
1 Capsule(s)
UPC/BARCODE
614299038400
IngredientAmount% DV
L-Theanine100 mg--

Other ingredients: Dicalcium Phosphate, Gelatin, Silicon Dioxide, Magnesium Stearate, Polyethylene Glycol, Acetic Acid, Sodium Lauryl Sulfate

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.
Precautions

Safety sealed. Do not use if printed seal under cap is cut, torn, or missing.

Keep out of the reach of children.

Warning: Pregnant or nursing women, individuals taking medication(s) or persons who have a health condition should consult their physician before using this product.

General Statements

Targeted health ~ Supports relaxation health

Quality value

Works gently and naturally to promote relaxation without drowsiness. Enhances endocrine function, stimulating some brain waves and leaving others unaffected.

"Satisfaction guaranteed or your money back."

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions: Adults - Take one capsule daily with food as a dietary supplement.

Storage

Store at 15(0) - 30(0) C (59(0) - 86(0) F).

Formulation

No artificial colors or flavors No gluten ~ No lactose ~ No trans fat

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.

General

137143 518632 USA646942

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

See for yourself

L-Theanine 100 mg by Exchange Select label

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

L-Theanine 100 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 100 mg by Exchange Select

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

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

L-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...

L-Theanine monograph & interactions

Other (inactive) ingredients: Dicalcium Phosphate, Gelatin, Silicon Dioxide, Magnesium Stearate, Polyethylene Glycol, Acetic Acid, Sodium Lauryl Sulfate. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Theanine 100 mg by Exchange Select Drug Interactions

Want to check YOUR meds against L-Theanine 100 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
565Drugs
172 Moderate 393 Minor

Ingredients driving the most interactions

L-Theanine 565

Individual Drug Interactions

The ingredients in L-Theanine 100 mg interact with 565 drugs. Click any drug to see the details.

1 of the 1 ingredient in L-Theanine 100 mg interact with drugs. Each result below shows which ingredient is responsible. L-Theanine

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Theanine 100 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-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
The maker

Brand information

Manufacturer and brand details for L-Theanine 100 mg, from the product label.

Exchange Select

See all Exchange Select products
Name
International Vitamin Corporation
City
Freehold
State
NJ
ZipCode
07728
Phone Number
1-866-927-5470
Pharmacist Counseling Corner

L-Theanine 100 mg by Exchange Select: Common Questions

Does L-Theanine 100 mg by Exchange Select interact with any medications?
Yes. Based on its ingredients, L-Theanine 100 mg 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?
L-Theanine 100 mg 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.
Can I take this while pregnant or breastfeeding?
Not enough safety data exists for either pregnancy or breastfeeding, so the safety information advises against it. Talk with your doctor or pharmacist about whether it's right for you in these situations — they can weigh your individual circumstances.
What are the main side effects?
Headaches, drowsiness, longer sleep, and more vivid dreams are the ones people report most often. A rare case of facial tics was reported in a child, but it wasn't clearly tied to L-Theanine use.
Does L-Theanine actually improve memory or thinking?
The evidence suggests it may help with cognitive function — that's rated as possibly effective. For age-related cognitive decline or Alzheimer's disease specifically, we don't have enough reliable evidence yet to say one way or the other.
Is this safe to take long-term?
L-Theanine is generally well tolerated in the short term, but long-term safety hasn't been well studied. If you're thinking about taking it regularly for months or longer, ask your doctor or pharmacist what we know.
What is L-Theanine and where does it come from?
L-Theanine is an amino acid naturally found in tea leaves. This supplement isolates it so you get a concentrated dose in capsule form.

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

Not sure if L-Theanine 100 mg 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.

L-Theanine 100 mg label
Go deeper

The Full Monographs Behind L-Theanine 100 mg’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

L-Theanine 100 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 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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