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Summary sheet: Theanine
Chemical Nomenclature
Common names Theanine, L-Theanine, L-γ-glutamylethylamide and N5-ethyl-L-glutamine
Systematic name N-ethyl-L-glutamine; (2S)-2-ammonio-5-(ethylamino)-5-oxopentanoate
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold 50 mg
Light 75 - 175 mg
Common 175 - 300 mg
Strong 300 - 500 mg
Heavy 500 mg +
Total 3 - 6 hours[1]
Onset 30 - 90 minutes[1]
Peak 1 - 3 hours
After effects 6 - 12 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


L-Theanine (also known as Theanine, L-γ-glutamylethylamide and N5-ethyl-L-glutamine) is an analog of the amino acids of glutamate and glutamine. It was discovered as a constituent of green tea in 1949 and in 1950 was isolated from gyokuro leaves, which have high theanine content.[2]

The appearance of the name "theanine" without a prefix is understood to imply the L-enantiomer, which is the form found in fresh teas and in some, but not all dietary supplements. The opposite D-enantiomer has far less studied pharmacologic properties, but is present in racemic chemical preparations, and substantially in some studied theanine supplements.

This compound is used as a nootropic for its calming and relaxing properties. It is often taken in combination with caffeine as it has been shown to mitigate its negative aspects, such as anxiety, increased blood pressure and diminished sleep quality, while possibly improving upon the positive aspects.[3][4][5][6] Its ability to enhance attention has been repeatedly verified.[6][7][8][9][10][11][12]

A recent systematic review of the effects of theanine and caffeine has confirmed that the combination seems to improve aspects of attention.[13] The combination of L-theanine and caffeine may improve attention more than caffeine alone.[7][8]


Theanine, or N-ethyl-L-glutamine, is an amino acid analogue of L-glutamine. Its structure is comprised of a five carbon straight chain carboxylic acid called pentanoic acid, which is bonded to an amino group at R2, and an additional ketone group at R5. Also substituted at R5 of the pentanoic group is an ethylamino chain connected at its amino constituent. Theanine is understood to refer to the levorotary enantiomer, which is well documented, rather than the relatively unresearched dextrorotary enantiomer.


Theanine is structurally similar to the excitatory neurotransmitter glutamate, and in accordance, binds to glutamate receptors, though with much lower affinity in comparison. Specifically, it binds to ionotropic glutamate receptors including the AMPA and kainate receptors and, to a lesser extent, the NMDA receptor.[14][15][16][17] It acts as an antagonist of the former two sites[17] and as an agonist of the latter site.[18] In addition, it inhibits glutamine transporters and glutamate transporters, and thus acts as reuptake inhibitor of glutamine and glutamate.[17][19][20]

Theanine increases dopamine, GABA, and glycine levels in various areas of the brain.[14][18][21][22] It also affects serotonin in a manner which is still a matter of debate in the scientific community, with separate studies showing increases and decreases in brain serotonin levels using similar experimental protocols.[22][23]

These various changes in neurotransmitter levels contribute to the calming and nootropic properties of theanine.

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

Cognitive effects

Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

Toxicity and harm potential

Theanine is non-addictive, is not known to cause brain damage, and has an extremely low toxicity relative to dose.[citation needed] There are relatively few physical side effects associated with acute theanine exposure. Various studies have shown that in reasonable doses in a careful context, it presents no negative cognitive, psychiatric or toxic physical consequences.[citation needed]

It is strongly recommended that one use harm reduction practices when using this substance.

Tolerance and addiction potential

Theanine is not habit-forming.

Tolerance to the effects of theanine are built up after prolonged and repeated usage. After noticeable tolerance has been built, it takes about 5 days for tolerance to be reduced by half and 10 days return to baseline. Theanine presents cross-tolerance with no other known compounds, meaning that after the consumption of theanine all other psychoactive compounds will not have a reduced effect.

Legal status


This legality section is a stub.

As such, it may contain incomplete or wrong information. You can help by expanding it.

Theanine is freely available to possess and distribute and is approved in most countries as a dietary supplement.

  • Canada Theanine is available as a dietary supplement and is freely available to possess and distribute in Canada.[citation needed]

See also

External links


  1. 1.0 1.1 Scheid, L., Ellinger, S., Alteheld, B., Herholz, H., Ellinger, J., Henn, T., Helfrich, H.-P., Stehle, P. (1 December 2012). "Kinetics of L-Theanine Uptake and Metabolism in Healthy Participants Are Comparable after Ingestion of L-Theanine via Capsules and Green Tea". The Journal of Nutrition. 142 (12): 2091–2096. doi:10.3945/jn.112.166371. ISSN 1541-6100. 
  2. Components of Gyokuro |
  3. Lyon, M. R., Kapoor, M. P., Juneja, L. R. (December 2011). "The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial". Alternative Medicine Review: A Journal of Clinical Therapeutic. 16 (4): 348–354. ISSN 1089-5159. 
  4. Lu, K., Gray, M. A., Oliver, C., Liley, D. T., Harrison, B. J., Bartholomeusz, C. F., Phan, K. L., Nathan, P. J. (October 2004). "The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans". Human Psychopharmacology. 19 (7): 457–465. doi:10.1002/hup.611. ISSN 0885-6222. 
  5. Kimura, K., Ozeki, M., Juneja, L. R., Ohira, H. (January 2007). "L-Theanine reduces psychological and physiological stress responses". Biological Psychology. 74 (1): 39–45. doi:10.1016/j.biopsycho.2006.06.006. ISSN 0301-0511. 
  6. 6.0 6.1 Kahathuduwa, C. N., Dassanayake, T. L., Amarakoon, A. M. T., Weerasinghe, V. S. (July 2017). "Acute effects of theanine, caffeine and theanine-caffeine combination on attention". Nutritional Neuroscience. 20 (6): 369–377. doi:10.1080/1028415X.2016.1144845. ISSN 1476-8305. 
  7. 7.0 7.1 Owen, G. N., Parnell, H., De Bruin, E. A., Rycroft, J. A. (August 2008). "The combined effects of L-theanine and caffeine on cognitive performance and mood". Nutritional Neuroscience. 11 (4): 193–198. doi:10.1179/147683008X301513. ISSN 1476-8305. 
  8. 8.0 8.1 Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., Scholey, A. B. (February 2008). "The effects of L-theanine, caffeine and their combination on cognition and mood". Biological Psychology. 77 (2): 113–122. doi:10.1016/j.biopsycho.2007.09.008. ISSN 0301-0511. 
  9. Einöther, S. J. L., Martens, V. E. G., Rycroft, J. A., De Bruin, E. A. (April 2010). "L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness". Appetite. 54 (2): 406–409. doi:10.1016/j.appet.2010.01.003. ISSN 1095-8304. 
  10. Kelly, S. P., Gomez-Ramirez, M., Montesi, J. L., Foxe, J. J. (August 2008). "L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance". The Journal of Nutrition. 138 (8): 1572S–1577S. doi:10.1093/jn/138.8.1572S. ISSN 1541-6100. 
  11. Giesbrecht, T., Rycroft, J. A., Rowson, M. J., De Bruin, E. A. (December 2010). "The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness". Nutritional Neuroscience. 13 (6): 283–290. doi:10.1179/147683010X12611460764840. ISSN 1476-8305. 
  12. Foxe, J. J., Morie, K. P., Laud, P. J., Rowson, M. J., Bruin, E. A. de, Kelly, S. P. (June 2012). "Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task". Neuropharmacology. 62 (7): 2320–2327. doi:10.1016/j.neuropharm.2012.01.020. ISSN 1873-7064. 
  13. Camfield, D. A., Stough, C., Farrimond, J., Scholey, A. B. (August 2014). "Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis". Nutrition Reviews. 72 (8): 507–522. doi:10.1111/nure.12120. ISSN 1753-4887. 
  14. 14.0 14.1 Nathan, P. J., Lu, K., Gray, M., Oliver, C. (2006). "The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent". Journal of Herbal Pharmacotherapy. 6 (2): 21–30. ISSN 1522-8940. 
  15. Kakuda, T., Nozawa, A., Sugimoto, A., Niino, H. (December 2002). "Inhibition by theanine of binding of [3H]AMPA, [3H]kainate, and [3H]MDL 105,519 to glutamate receptors". Bioscience, Biotechnology, and Biochemistry. 66 (12): 2683–2686. doi:10.1271/bbb.66.2683. ISSN 0916-8451. 
  16. Kakuda, T. (August 2011). "Neuroprotective effects of theanine and its preventive effects on cognitive dysfunction". Pharmacological Research. 64 (2): 162–168. doi:10.1016/j.phrs.2011.03.010. ISSN 1096-1186. 
  17. 17.0 17.1 17.2 Kakuda, T. (December 2002). "Neuroprotective effects of the green tea components theanine and catechins". Biological & Pharmaceutical Bulletin. 25 (12): 1513–1518. doi:10.1248/bpb.25.1513. ISSN 0918-6158. 
  18. 18.0 18.1 Wakabayashi, C., Numakawa, T., Ninomiya, M., Chiba, S., Kunugi, H. (February 2012). "Behavioral and molecular evidence for psychotropic effects in L-theanine". Psychopharmacology. 219 (4): 1099–1109. doi:10.1007/s00213-011-2440-z. ISSN 1432-2072. 
  19. Sugiyama, T., Sadzuka, Y., Tanaka, K., Sonobe, T. (30 April 2001). "Inhibition of glutamate transporter by theanine enhances the therapeutic efficacy of doxorubicin". Toxicology Letters. 121 (2): 89–96. doi:10.1016/s0378-4274(01)00317-4. ISSN 0378-4274. 
  20. Sugiyama, T., Sadzuka, Y. (5 December 2003). "Theanine and glutamate transporter inhibitors enhance the antitumor efficacy of chemotherapeutic agents". Biochimica Et Biophysica Acta. 1653 (2): 47–59. doi:10.1016/s0304-419x(03)00031-3. ISSN 0006-3002. 
  21. Yamada, T., Terashima, T., Wada, K., Ueda, S., Ito, M., Okubo, T., Juneja, L. R., Yokogoshi, H. (29 September 2007). "Theanine, r-glutamylethylamide, increases neurotransmission concentrations and neurotrophin mRNA levels in the brain during lactation". Life Sciences. 81 (16): 1247–1255. doi:10.1016/j.lfs.2007.08.023. ISSN 0024-3205. 
  22. 22.0 22.1 Yokogoshi, H., Kobayashi, M., Mochizuki, M., Terashima, T. (May 1998). "Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats". Neurochemical Research. 23 (5): 667–673. doi:10.1023/a:1022490806093. ISSN 0364-3190. 
  23. Yokogoshi, H., Mochizuki, M., Saitoh, K. (April 1998). "Theanine-induced reduction of brain serotonin concentration in rats". Bioscience, Biotechnology, and Biochemistry. 62 (4): 816–817. doi:10.1271/bbb.62.816. ISSN 0916-8451. 
  24. Park, S.-K., Jung, I.-C., Lee, W. K., Lee, Y. S., Park, H. K., Go, H. J., Kim, K., Lim, N. K., Hong, J. T., Ly, S. Y., Rho, S. S. (April 2011). "A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study". Journal of Medicinal Food. 14 (4): 334–343. doi:10.1089/jmf.2009.1374. ISSN 1557-7600.