L-Theanine
- Effective dose
- 100–200 mg
- Evidence
- 3/5· Moderate
Last updated June 1, 2026
What it is
L-theanine is an amino acid found mainly in tea leaves that influences brain activity, increasing alpha waves associated with relaxed alertness. It is most often used alongside caffeine, where it appears to smooth caffeine's stimulant edge.
Benefits
Paired with caffeine, around 200 mg of L-theanine improves attention, reaction time, and focus while reducing distraction, with effects often stronger than either compound alone. A typical effective pairing is 200 mg L-theanine with about 160 mg caffeine.
When to take it
Take alongside caffeine before a task requiring focus; commonly paired at roughly a 1:1 to 2:1 theanine-to-caffeine ratio.
Side effects
Very well tolerated with few reported side effects; may cause mild drowsiness in some people at higher doses.
Sources
Products containing L-Theanine
No products in our database contain this ingredient yet.