L-Theanine: uses, dosing, side effects & brands
L-Theanine is a medicine sold in the U.S. under one brand. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Sold as
- L-Theanine
- Generic available?
- Yes
Can you take l-theanine with…?
Source-cited answers for the combinations people actually ask about — each with a verdict and what to watch for.
Every l-theanine product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: L-Theanine.
What people report to the FDA about l-theanine
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 286 reports naming l-theanine, and the FDA flagged 57% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- anxiety33 reports
- fatigue30 reports
- headache22 reports
- insomnia22 reports
- nausea21 reports
- depression19 reports
- dizziness19 reports
- arthralgia18 reports
Read these as a signal, not a rate. A report does not mean l-theanine caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is L-Theanine?
Amino acid from tea taken for calm focus, often with caffeine.
Can you take l-theanine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run l-theanine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
Is there a generic l-theanine?
Yes. Our catalog lists 1 generic l-theanine product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
What should I avoid while taking l-theanine?
Other medicines: we hold source-cited interaction answers for Can you take ashwagandha with L-theanine?. This is what the FDA label and our cited sources say — it is not a complete list. Your pharmacist can check your own combination.
Cite this page
- APA
- pharmaranks. (2026, July 24). L-Theanine: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/l-theanine
- MLA
- “L-Theanine: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/l-theanine.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for l-theanine on DailyMed (NIH) ↗.