L-Theanine and medications.
L-Theanine is in the Distil supplement database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.
L-theanine is an amino acid found in tea that tends to promote a calm, settled state without sedating you. Its best-supported uses are anxiety and sleep onset, where the evidence sits at Grade A; the cognitive case is a step weaker at Grade B. Trials by Nobre, Kimura and Hidese point to reduced stress markers and easier sleep onset, with Haskell showing focus benefits when it is combined with caffeine. Typical doses are 100 to 200mg, with 200mg before bed for sleep onset and 100mg paired with caffeine at a roughly 4:1 theanine-to-caffeine ratio for focus. On interactions, caffeine is the standout positive pairing: theanine smooths the stimulation and reduces jitteriness, and it stacks well with magnesium glycinate for sleep. The one to watch is sedatives and benzodiazepines, where the effects on the central nervous system are additive. It is very well tolerated otherwise, with mild drowsiness only at higher doses alongside sedating compounds.
Below are the 3 documented pairs we have explicitly assessed for L-Theanine: 3 green. The pairs cluster around 2 mechanisms: Additive blood-pressure lowering and Additive CNS depression. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 15 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Additive blood-pressure lowering
Green Does interact with Amlodipine?
L-theanine can take the edge off a stress-driven rise in blood pressure, but it does not lower resting blood pressure the way a blood-pressure medicine does. At normal supplement doses it is not expected to push your blood pressure too low when taken with amlodipine. If you monitor at home and see readings lower than usual, mention it to your GP.
Evidence: Supported by human study data.
Additive CNS depression
Green Does interact with Alprazolam?
L-theanine is calming but it does not act like a sedative, so it is not expected to add to the drowsiness of a benzodiazepine such as alprazolam. In a hospital trial it produced far less sedation than alprazolam itself and did not impair thinking. If you feel unusually drowsy on this combination, the cause is far more likely to be the alprazolam, and you should speak to your prescriber.
Evidence: Supported by human study data.
Green Does interact with Diazepam?
L-theanine is calming but it does not act like a sedative, so it is not expected to add to the drowsiness of a benzodiazepine such as diazepam. In a hospital trial it produced far less sedation than a benzodiazepine and did not impair thinking. If you feel unusually drowsy on this combination, the cause is far more likely to be the diazepam, and you should speak to your prescriber.
Evidence: Supported by human study data.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyA full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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