What is the recommended dosage for L-Theanine?

General: 100-200 mg/day; With Caffeine: 200 mg L-theanine + 100 mg caffeine

What are the side effects of L-Theanine?

Potential side effects include: Generally very well-tolerated, Mild drowsiness in sensitive individuals, Mild headache (rare).

L-theanine is an amino acid found primarily in green and black tea. It has been studied for its ability to promote alpha brain wave activity, which is associated with a state of calm alertness. Research suggests it may support attention, focus, and relaxation without sedation.

What dosage of L-Theanine has been used in studies?

Clinical studies have commonly used 100 mg to 400 mg of L-theanine daily. A popular research dose is 200 mg taken once or twice daily. Some studies have combined L-theanine with caffeine for synergistic effects on attention. Consult your healthcare provider for guidance.

What are the potential side effects of L-Theanine?

L-theanine has a strong safety profile and is generally well tolerated. Rare side effects may include headache and gastrointestinal discomfort. It may enhance the effects of blood pressure-lowering medications. Consult your healthcare provider if you take antihypertensive drugs.

L-Theanine

amino_acid

Also known as: Theanine, Gamma-Glutamylethylamide, Suntheanine

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About

L-Theanine is an amino acid found primarily in green tea that crosses the blood-brain barrier to increase alpha brainwave activity associated with calm alertness. The L-theanine + caffeine combination is one of the most replicated nootropic pairings, consistently showing improvements in attention, task switching, and alertness without jitteriness.

How It Works

Crosses the blood-brain barrier and increases alpha brainwave activity associated with calm alertness; enhances GABA, serotonin, and dopamine levels; synergizes with caffeine to improve attention without jitteriness; reduces glutamate excitotoxicity.

Evidence For Conditions

Condition	Grade	Studies	Participants
Attention & Focus Difficulties	B	20	1500	View →
Anxiety-Related Cognitive Impairment	C	8	500	View →
Sleep-Related Cognitive Impairment	C	6	400	View →

Side Effects

Generally very well-tolerated
Mild drowsiness in sensitive individuals
Mild headache (rare)

Drug & Supplement Interactions

Antihypertensive drugs (may enhance blood pressure lowering)
Stimulant medications (counteracts some stimulant side effects)
Sedative medications (additive calming effects)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Acetyl-L-Carnitine N-Acetyl Cysteine Taurine

Quick Facts

Dosage: General: 100-200 mg/day; With_Caffeine: 200 mg L-theanine + 100 mg caffeine
Forms: capsule tablet powder
Natural Sources: Green tea (Camellia sinensis), Certain mushrooms
Upper Limit: 900 mg/day (no adverse effects observed in studies)
Best Time: Morning or as needed; rapid onset (30-60 minutes)

Evidence Summary

Attention & Focus Difficulties B

Anxiety-Related Cognitive Impairment C

Sleep-Related Cognitive Impairment C

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.