From the databaseWhat the row says.
Every entry follows the same shape: what is happening, the mechanism, and the recommendation.
Scope
Supplement × Prescription
Last verified
June 4, 2026
CautionEmerging evidence
What is happening. L-Theanine may have calming effects and could add to levetiracetam-related fatigue or dizziness.
Mechanism. Potential additive CNS effects.
Recommendation. Use cautiously during dose changes and avoid hazardous activities if impaired.
Stack Score
How it moves the number.
Effect on the composite score
If both L-Theanine and Levetiracetam Extended-Release are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are at /methodology/stack-score.
SourcesSources, by evidence tier.
Every claim on this page is cited. PMIDs link straight to PubMed.
Reference material
1- 1U.S. National Library of Medicine. Levetiracetam extended-release tablets US Prescribing Information. 2025.Needs sourceNo link