Supplement·Interactions·Reviewed June 9, 2026
L-Theanine interactions.
L-Theanine has 42 documented interactions in the NutriStack database: 15 that need timing or caution and 27 that work synergistically. The full list, with what each pairing does, is below.
L-Theanine at a glance.
A quick, data-grounded summary. The full table is below.
L-Theanine has 42 documented interactions in the NutriStack database: 15 that need timing or caution and 27 that work synergistically. The full list, with what each pairing does, is below.
Everything that interacts with l-theanine.
Every supplement and medication in the NutriStack database with a documented interaction with this substance, highest-severity first. Open any pair for the mechanism and sources.
| Substance | Interaction | What happens |
|---|---|---|
| Azelastine | Caution | L-theanine may compound fatigue or reduced alertness from azelastine. |
| Clonidine | Caution | L-Theanine may add to clonidine-related sedation or blood pressure lowering. |
| Desloratadine | Caution | L-theanine may compound mild antihistamine-related fatigue or reduced alertness. |
| Dicyclomine | Caution | L-theanine can be calming and may compound dicyclomine-associated sedation or dizziness. |
| Diltiazem | Caution | L-Theanine modestly lowers stress-induced blood pressure increases and has mild relaxing effects on vascular tone. Layered on top of diltiazem's... |
| Doxepin | Caution | L-Theanine may have calming or sedating effects that can add to doxepin. |
| DSIP (Delta Sleep-Inducing Peptide) | Caution | L-theanine may add relaxation or sedation and confound sleep tracking. |
| Lacosamide | Caution | L-Theanine may add calming effects to lacosamide-related somnolence or dizziness. |
| Levetiracetam Extended-Release | Caution | L-Theanine may have calming effects and could add to levetiracetam-related fatigue or dizziness. |
| Levocetirizine | Caution | L-theanine may compound fatigue or reduced alertness from levocetirizine. |
| Lurasidone | Caution | L-Theanine may add calming or sedating effects to lurasidone. |
| Metoprolol | Caution | L-Theanine blunts stress-induced rises in blood pressure and heart rate in high-stress-responder subjects. Combined with metoprolol, the effect is... |
| Nicotine | Caution | L-theanine may blunt the subjective stimulation and arousal from nicotine, but it does not reduce nicotine's addictive potential or cardiovascular... |
| Phenobarbital | Caution | L-Theanine may add calming or sedating effects to phenobarbital. |
| Selank | Caution | L-theanine may add calming effects and confound response tracking. |
| American Ginseng | Synergy | American ginseng can acutely sharpen working memory and reaction time, while L-theanine promotes calm focus by increasing alpha brain wave activity;... |
| Ashwagandha | Synergy | Both are studied for relaxation, perceived-stress, and calm-focus markers; direct combination evidence is limited. |
| Bacopa Monnieri | Synergy | Bacopa monnieri and L-theanine are commonly combined for cognitive support, with Bacopa supporting memory consolidation and L-theanine promoting... |
| Caffeine | Synergy | Theanine may smooth caffeine-related jitteriness while preserving attention benefits. |
| Chamomile | Synergy | Both are mild calming supplements and may be complementary. |
| GABA | Synergy | Complementary calming effect, with L-theanine promoting relaxed alertness and increasing alpha brain-wave activity alongside GABA's inhibitory... |
| Glycine | Synergy | Both amino acids support sleep through different routes, so combining them may reduce pre-sleep tension and improve sleep quality more than either... |
| Gotu Kola | Synergy | Gotu kola has traditional and preliminary use for nervous tension, and L-theanine promotes a calm, alert state. Used together they may provide... |
| Green Tea Extract | Synergy | L-theanine smooths the caffeine stimulation from green tea extract, improving sustained attention while reducing jitteriness and the post-caffeine... |
| Huperzine A | Synergy | L-theanine may smooth anxiety or overstimulation from nootropic stacks, but it does not prevent cholinergic toxicity. |
| Jujube | Synergy | Both are calming and may be complementary for evening relaxation. |
| L-Tyrosine | Synergy | L-Tyrosine supports catecholamine production for alertness under stress while L-theanine promotes calm focus, so the pair tends to deliver activated... |
| Lavender | Synergy | Both can support calm without strong evidence of dangerous interaction. |
| Lemon Balm | Synergy | Both support calm without strong respiratory depression, but additive drowsiness is possible. |
| Magnesium Citrate | Synergy | L-theanine and magnesium are both studied for relaxation-related markers, but direct combination evidence is limited. |
| Magnesium Glycinate | Synergy | L-theanine and magnesium are both studied for relaxation-related markers, but direct combination evidence is limited. |
| Magnesium L-Threonate | Synergy | L-theanine and magnesium are both studied for relaxation-related markers, but direct combination evidence is limited. |
| Magnesium Malate | Synergy | L-theanine and magnesium are both studied for relaxation-related markers, but direct combination evidence is limited. |
| Magnesium Taurate | Synergy | L-theanine and magnesium are both studied for relaxation-related markers, but direct combination evidence is limited. |
| Magnolia Bark | Synergy | Both may support calm with generally mild tolerability concerns. |
| Melatonin | Synergy | L-theanine eases pre-sleep mental tension while melatonin signals sleep timing, so together they can shorten time to fall asleep and improve... details → |
| Passionflower | Synergy | Both calm the nervous system mainly through GABA pathways, so combining them can produce additive anxiety-reducing and sleep-supporting effects. |
| Propranolol | Synergy | Both L-theanine and propranolol blunt the cardiovascular response to acute stress. The combination can produce slightly greater anxiolytic effects,... |
| Rhodiola Rosea | Synergy | L-theanine takes the edge off rhodiola's mild stimulating effect, supporting calm, focused stress resilience. |
| Taurine | Synergy | Taurine and L-theanine both promote GABAergic and calming neurotransmission, giving additive relaxation without sedation. |
| Valerian Root | Synergy | Valerian root provides GABAergic sedation while L-theanine promotes calm without strong sedation, giving a complementary relaxation effect that is... |
| Vitamin B6 | Synergy | Both support GABA production. B6 is the cofactor for glutamic acid decarboxylase, which synthesizes GABA. L-theanine increases GABA levels. |
The full l-theanine profile.
Benefits, dosing by goal, forms, and the cited evidence for this supplement.
Common l-theanine questions.
Quick answers drawn from the table above.
What interacts with L-Theanine?
In the NutriStack database, L-Theanine has 42 documented interactions with other supplements and medications. The most notable include Azelastine, Clonidine, Desloratadine, Dicyclomine, and Diltiazem.
What works well with L-Theanine?
L-Theanine pairs synergistically with American Ginseng, Ashwagandha, Bacopa Monnieri, Caffeine, and Chamomile in the NutriStack database. Synergy still depends on dose and timing; open any pair for the detail.
Can you take L-Theanine with Azelastine?
NutriStack classifies the L-Theanine and Azelastine pairing as caution: L-theanine may compound fatigue or reduced alertness from azelastine. Avoid combining with other calming products if drowsiness occurs.
Check your whole stack
See how l-theanine fits your routine.
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