Meta Information
ID:l-theanine
Name:
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-05-21T22:30:00Z
Model
phase-a-upgrade-claude-sonnet-4.6
Interactions
Target id:
/class/antihypertensives
Target name:
Antihypertensive Medications
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Theanine may lower blood pressure, and combining it with antihypertensive medications could lead to an excessive drop (hypotension), causing dizziness or fainting.
Actionable advice:
Blood pressure should be monitored closely, and it is important to talk to a physician before combining L-Theanine with blood pressure-lowering drugs.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Theanine, a naturally occurring non-proteinic amino acid found in tea leaves, has demonstrated wide-ranging physiological activity, from lowering blood pressure to enhancing the anti-tumor activity of chemotherapeutic drugs.
Label source:
PubMed: Analysis of derivatized and underivatized theanine enantiomers by high-performance liquid chromatography/atmospheric pressure ionization-mass spectrometry. (PMID 14755608)
Action type:
monitor
Target id:
/intervention/caffeine
Target name:
Caffeine
Severity:
minor
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Theanine works synergistically with caffeine to promote a state of calm focus, enhancing cognitive performance while reducing caffeine-induced anxiety and jitteriness.
Actionable advice:
L-Theanine is generally best taken at the same time as caffeine, often in a 2:1 ratio (Theanine:Caffeine), for optimal effect.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.
Label source:
PubMed: Effect of Green Tea Phytochemicals on Mood and Cognition. (PMID 28056735)
Action type:
informational_none
Target id:
/circadian/sleep
Target name:
Going to Sleep
Severity:
moderate
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
0.5
Description:
L-Theanine promotes relaxation and alpha brain wave activity, which can help improve sleep quality and reduce the time it takes to fall asleep without causing direct sedation.
Actionable advice:
It is best taken 30-60 minutes before the intended bedtime to aid with sleep onset and quality.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
L-Theanine (γ-glutamylethylamide), an amino acid naturally found abundant in tea leaves, has anxiolytic effects via the induction of α brain waves without additive and other side effects associated with conventional sleep inducers.
Label source:
PubMed: Journal of the American College of Nutrition (2015)
Source url:
Exact phrase from label:
Previous studies have reported that consumption of L-theanine can help to aid relaxation, without causing sedation or adversely impacting cognitive function.
Label source:
PubMed: Nutritional neuroscience (2026)
Source url:
Exact phrase from label:
Some studies suggest l-theanine may increase alpha waves in the brain associated with relaxation and selective attention, reduce stress and anxiety, and improve sleep quality, though findings are often inconsistent.
Label source:
PubMed: Nutrition research (New York, N.Y.) (2025)
Action type:
separate
Target id:
/class/cns-depressants
Target name:
CNS Depressants (Sedatives) (Pharmacologic)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Theanine promotes relaxation and may have additive effects with sedative medications (e.g., benzodiazepines, barbiturates, sleep aids), potentially causing excessive drowsiness.
Actionable advice:
Caution is warranted, and it is important to talk to a healthcare provider before combining with any sedative medications.
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Exact phrase from label:
When combined with other CNS depressants (benzodiazepines, sedative-hypnotics, certain antipsychotics), monitor for additive sedation
Label source:
Expert review: L-theanine has documented anxiolytic and sleep-promoting effects mediated through GABA-A modulation and AMPA receptor inhibition. Clinical guidance notes that L-theanine may cause dose-dependent CNS depression, with additive sedation when combined with pharmacologic CNS depressants such as benzodiazepines.
Action type:
informational_none
Target id:
/class/stimulants
Target name:
Stimulant Medications
Severity:
minor
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Theanine can reduce the stimulating effects and unwanted side effects (like jitteriness and anxiety) of stimulant medications used for conditions like ADHD.
Actionable advice:
L-Theanine may blunt the peak effects and side effects of stimulant medications.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
CAF alone increased state anxiety compared to PLA (p
=
0.021), while CAF+THE reduced anxiety to below placebo levels (8% incidence vs 33%). Trait anxiety was lower in CAF+THE compared to CAF (p
=
0.018). The prevalence of caffeine-induced tachycardia (92%) was notably reduced under CAF+THE (17%).
Label source:
PubMed: Journal of the International Society of Sports Nutrition (2025)
Source url:
Exact phrase from label:
Caffeine increased self-rated alertness and jitteriness and blood pressure. Theanine antagonised the effect of caffeine on blood pressure but did not significantly affect jitteriness, alertness or other aspects of mood.
Label source:
PubMed: Psychopharmacology (2008)
Source url:
Exact phrase from label:
The observations that l-theanine has been shown to inhibit caffeine's stimulatory effects and that caffeine produces precipitated withdrawal signs in opioid-addicted monkeys and some opioid withdrawal signs in some normal monkeys, suggest that l-theanine may suppress opioid withdrawal signs.
Label source:
PubMed: Pharmacology, biochemistry, and behavior (2012)
Action type:
informational_none
Target id:
/dietary/high-protein-meal
Target name:
High-Protein Meal
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
0.5
Hours after target:
1.5
Description:
L-Theanine competes for transport across the blood-brain barrier with other large neutral amino acids found in protein, which may slightly reduce its central effects.
Actionable advice:
For most noticeable cognitive or calming effects, L-Theanine is best taken at least 30 minutes before or 90 minutes after a high-protein meal.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
[L-theanine (N-ethyl-gamma-glutamine) is the main amino acid in tea leaves.] Absorption of tryptophan (TRP) across the gut epithelium is potentially modulated by competing large neutral amino acids (LNAAs), which could affect the appearance of TRP and its metabolites in the bloodstream.
Label source:
Expert review: L-theanine is a large neutral amino acid (LNAA) that crosses the blood-brain barrier via the LNAA transporter (LAT1), which is shared with other large neutral amino acids including phenylalanine, leucine, isoleucine, and valine found in dietary protein. High protein intake increases competition for this transporter, potentially reducing L-theanine's CNS bioavailability.
Action type:
separate
Target id:
/condition/hypotension
Target name:
Hypotension (Low Blood Pressure)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Theanine may lower blood pressure, which could cause symptoms like dizziness or fainting in individuals who already have hypotension.
Actionable advice:
If you have low blood pressure, consult a doctor before using and monitor for symptoms.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
When SHR were injected with various amounts of theanine (0, 500, 1000, 1500, and 2000 mg/kg), the change was dose-dependent, and a significant decrease in blood pressure was observed with the high doses (1500 and 2000 mg/kg).
Label source:
PubMed: Bioscience, biotechnology, and biochemistry (1995)
Source url:
Exact phrase from label:
The results after the mental tasks showed that L-theanine significantly inhibited the blood-pressure increases in a high-response group, which consisted of participants whose blood pressure increased more than average by a performance of a mental task after placebo intake.
Label source:
PubMed: Journal of physiological anthropology (2012)
Source url:
Exact phrase from label:
Theanine antagonised the effect of caffeine on blood pressure but did not significantly affect jitteriness, alertness or other aspects of mood.
Label source:
PubMed: Psychopharmacology (2008)
Action type:
monitor
Target id:
/condition/pregnancy
Target name:
Pregnancy
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
There is a lack of sufficient safety data regarding the use of L-Theanine supplements during pregnancy.
Actionable advice:
L-Theanine supplements should not be used during pregnancy.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
There isn’t enough safety data, so it’s best to avoid it unless your healthcare provider says otherwise.
Label source:
Anecdotal: Cleveland Clinic
Action type:
avoid
Target id:
/condition/lactation
Target name:
Breastfeeding (Lactation)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
It is unknown if L-Theanine passes into breast milk or what its effects on a nursing infant might be.
Actionable advice:
L-Theanine supplements should not be used while breastfeeding.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
It is not known if theanine passes into breast milk.
Label source:
Anecdotal: WebMD
Action type:
avoid
Target id:
/class/chemotherapy-radiation
Target name:
Chemotherapy Medications
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Some preclinical evidence suggests L-Theanine may enhance the anti-tumor effects of certain chemotherapy drugs (e.g., doxorubicin) while potentially reducing their side effects.
Actionable advice:
This is best not used with chemotherapy without explicit approval and supervision from an oncologist.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
the same chemotherapy alone.
Label source:
Action type:
avoid
Target id:
/procedure/surgery
Target name:
Scheduled Surgery
Severity:
minor
Interaction type:
adverse
Nature:
temporal
Temporal spacing:
Hours before target:
336
Hours after target:
null
Description:
Because L-Theanine can affect blood pressure, there is a theoretical concern it might interfere with blood pressure control during and after surgery.
Actionable advice:
L-Theanine is best discontinued at least 2 weeks before any scheduled surgery.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The results after the mental tasks showed that L-theanine significantly inhibited the blood-pressure increases in a high-response group, which consisted of participants whose blood pressure increased more than average by a performance of a mental task after placebo intake.
Label source:
PubMed: Journal of physiological anthropology (2012)
Source url:
Exact phrase from label:
When SHR were injected with various amounts of theanine (0, 500, 1000, 1500, and 2000 mg/kg), the change was dose-dependent, and a significant decrease in blood pressure was observed with the high doses (1500 and 2000 mg/kg).
Label source:
PubMed: Bioscience, biotechnology, and biochemistry (1995)
Source url:
Exact phrase from label:
The primary objective was to study and compare the effects of L-theanine and GABA on preoperative anxiety, sedation, and cognition in patients posted for major elective surgeries.
Label source:
PubMed: Journal of anaesthesiology, clinical pharmacology (2025)
Action type:
avoid
Target id:
/class/herbal-sedatives
Target name:
Calming Herbs (e.g., Ashwagandha, Valerian, Lemon Balm) (Herbal Additive)
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Combining L-Theanine with other supplements known for their calming or anxiolytic properties may result in an enhanced, additive relaxation effect.
Actionable advice:
Lower doses of each supplement may help when combining, to assess tolerance for drowsiness.
Validation status:
unvalidatable
Evidence tier:
tier_e
Evidence basis:
unvalidatable
Evidence anchors:
Source url:
Scientific literature support not found
Exact phrase from label:
Label source:
Expert review: L-theanine's anxiolytic effects via GABA modulation are additive with other GABAergic/adaptogenic calming herbs (valerian acts as GABA agonist; ashwagandha modulates GABA-A receptors; lemon balm inhibits GABA transaminase). Combined use produces enhanced relaxation through complementary inhibitory CNS mechanisms.
Action type:
informational_none