Amino Acid

L-Theanine

Also known as: Theanine

Evidence

Calming amino acid from tea that promotes relaxation without sedation. Synergistic with caffeine for focused calm.

Find the best L-Theanine supplements — free

See L-Theanine products scored on dose & form, then track your intake in the app.

Open app →

Daily target & upper limit

200 mg / day

L-Theanine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:

L-Theanine dosage reference →

Primary uses

Relaxation
Focus
Sleep support
Anxiety relief

How it works

Increases alpha brain waves
Modulates GABA, dopamine, serotonin
Crosses blood-brain barrier

Dosage

Typical range: 100-400 mg daily
Timing: Any time; with caffeine for focus
With food: Optional
Duration: Safe long-term
Special populations: Anxious, need calm focus

Forms

Capsules
Powder
Tea

Safety

Common side effects

Very well tolerated

Contraindications

None

Products containing L-Theanine

Top-scoring supplements in our catalog that list L-Theanine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Known interactions

Synergywith caffeine
L-theanine smooths caffeine's effects

Evidence notes

Well-studied for calm focus

Grade A: Multiple well-designed human trials support the main claims.

Cited research for L-Theanine

Clinical studies referenced across Formulate guides that mention l-theanine. Each links to the full study page with PubMed source + the guides that cite it.

L-Theanine compared head-to-head

Related in Amino Acid

Check a full stack

Formulate's free interaction checker lets you paste in any combination of supplements and medications at once — every pairing flags severity, timing, and cited evidence.

Open the checker

Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.