L-theanine is an amino acid that is found abundantly in both black and green tea as well as certain mushrooms. However, using L-theanine supplements is better to ensure a daily dose. This easy-to-find amino acid improves symptoms of stress and anxiety while aiding insomnia. 

Even though L-theanine is mainly used to help people relax and calm down, you should ask your doctor before using it. This common amino acid impacts the brain chemicals, including dopamine and serotonin, effectively improving mental function. 

L-Theanine For Anxiety: Benefits

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The main benefits you will come across with the use of this amino acid are related to reducing stress and anxiety. However, there are certain health areas that it also affects. Let’s take a look at the benefits this simple amino acid has.

Relieves stress and anxiety

Tea, a natural source of l-theanine, is soothing and calms the mind down without making you feel groggy. A review of 5 different studies, including 4 trials, showed that participants who used L-theanine faced less anxiety and stress disorders. [1] [2]

Another research revealed that using L-theanine reduced symptoms of schizophrenia. 

Improves Focus

When used alongside caffeine, L-theanine can boost focus and concentration. A study combined 97mg of L-theanine with 40mg in a group of young people to improve focus for tasks requiring extra attention. The participants stated that they felt less exhausted and could focus more. [3] 

Boosts Immunity 

Some studies claim that using L-theanine could boost overall immunity and protect one from upper respiratory tract infections. Another similar study found that using L-theanine with green tea prepared a good preventive concoction for the flu. L-theanine can also be used to treat inflammation in the intestine. [4] [5]

Treats Cancer and Tumors 

The research found that L-theanine amplifies the impact of some chemotherapy drugs used for tumors. This finding is directly linked to the amino acid’s capacity to treat cancer. Studies have also shown that people who drink tea regularly have lower chances of developing cancer. [6

Controls Blood Pressure 

A study revealed that people with high blood pressure after a stressful act used L-theanine to reduce it. Another study also showed that L-theanine impacted sleep and improved sleeping patterns by relaxing the body. 

L-Theanine For Anxiety: Side Effects

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Even though no side effects are reported for using L-theanine naturally or through supplements, other things included in the supplements could be risky to use. L-theanine is researched to positively impact tumors, but teas with L-theanine for tumors may contain harmful ingredients. 

A medical institute claims that EGCG, a polyphenol found in green tea, may reduce the effect of some chemotherapy drugs. Moreover, consuming too much green or black tea may cause nausea, an upset stomach, and irritability. 

Pregnant and nursing women must also be wary of tea so they are not over-caffeinated. If you are about to use L-theanine for anxiety and stress, then you should consult your healthcare provider before using any supplements. 

L-Theanine: Dosage

Before using L-theanine for anxiety, it is suggested that you ask your doctor for the prescribed dosage. However, the recommended L-theanine dosage for anxiety is 200mg to 400mg. If you consume more than 1200mg of the amino acid, there is a risk of severe side effects. Combining L-theanine with specific drugs may have an enhanced impact on anxiety. 

L-Theanine For Anxiety and Depression

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L-theanine is a magic drug that has a positive impact on brain function. It has a direct effect on neurotransmitters like dopamine and serotonin. This action increases calmness in the body and improves the functions of neurons. 

By doing so, L-theanine regulates emotions, improves concentration, and balances the mood. This amino acid also prevents cortisol, a stress hormone, from harming the brain. This way, you can improve stress management and not get affected by anxiety or depression. 

L-theanine also affects brain waves and forces them to use the alpha wave pattern, which keeps the body relaxed. This supplement can reduce signs of anxiety and stop you from feeling depressed in stressful situations. 

When To Take L-Theanine For Anxiety?

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You should let your doctor decide the dosage and timings of L-theanine for anxiety. However, the timing of the dose depends on what you wish to attain. Consuming L-theanine in the morning will help you concentrate on your daily tasks and improve focus. 

If you want a relaxed and easy sleep, you can consume L-theanine at night. If you take your dosage at night, then try consuming it at least 30 minutes or an hour before your bedtime. 

Best L-Theanine For Anxiety

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If you’re searching for the best L-theanine supplement for anxiety that can show you effective and quick results, you should know what form to buy. Know the active ingredients in the supplement you buy since L-theanine when paired with certain drugs or minerals, can have a better impact. Look for ingredients that include some or all of the following: 

  • Melatonin 
  • Caffeine 
  • Passionflower 
  • Valerian root
  • Chamomile 

However, if you’re strictly looking for L-theanine supplements for anxiety and stress, then you should skip the extra ingredients and get pure L-theanine. A simple form of this supplement will help improve anxiety symptoms as compared to a combination of other ingredients that may have opposite effects. 

The Bottomline

L-theanine has been researched to be effective for anxiety and stress disorders. As a naturally found ingredient, it has little to no side effects unless paired with the wrong ingredients. Moreover, L-theanine does more for the body than reducing stress and anxiety. It also enhances the immune system, provides mental clarity, and improves performance.

However, more research is required regarding its usage, so always ask your doctor before using any supplement, even if it is naturally sourced. If you’re going to use L-theanine for anxiety, then you should also observe your tea intake so there is no overdose of the amino acid. 


L-theanine works as a relaxant in the body. Research shows that L-theanine also increases serotonin and dopamine levels in the body. 
L-theanine can’t be found in the regular things we eat on a daily basis. However, items rich in amino acids include green and black tea. L-theanine can also be found in some varieties of mushrooms. 
L-theanine or its supplements can interact with certain things like stimulants, sedatives, and even medication for blood pressure. So be careful when consuming L-theanine or ask your doctor before using it. 

Disclaimer: This article is only a guide. It does not substitute the advice given by your healthcare professional. Before making any health-related decision, consult your healthcare professional.

Editorial References and Fact-Checking

  1. Ritsner, M. S., Miodownik, C., Ratner, Y., Shleifer, T., Mar, M., Pintov, L., & Lerner, V. (2010). L-Theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder. The Journal of Clinical Psychiatry, 72(01), 34–42. https://doi.org/10.4088/jcp.09m05324gre
  2. Everett, J., Gunathilake, D., Dufficy, L., Roach, P., Thomas, J., Upton, D., & Naumovski, N. (2016). Theanine consumption, stress and anxiety in human clinical trials: A systematic review. Journal of Nutrition & Intermediary Metabolism, 4, 41-42. https://doi.org/10.1016/j.jnim.2015.12.308
  3. Giesbrecht, T., Rycroft, J. A., Rowson, M. J., & De Bruin, E. A. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional neuroscience, 13(6), 283–290. https://doi.org/10.1179/147683010X12611460764840
  4. Matsumoto, K., Yamada, H., Takuma, N., Niino, H., & Sagesaka, Y. M. (2011). Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. BMC complementary and alternative medicine, 11, 15. https://doi.org/10.1186/1472-6882-11-15
  5. Mijong Park and others, Green Tea Consumption Is Inversely Associated with the Incidence of Influenza Infection among Schoolchildren in a Tea Plantation Area of Japan, The Journal of Nutrition, Volume 141, Issue 10, October 2011, Pages 1862–1870, https://doi.org/10.3945/jn.110.137547
  6. Khan, N., & Mukhtar, H. (2013). Tea and health: studies in humans. Current pharmaceutical design, 19(34), 6141–6147. https://doi.org/10.2174/1381612811319340008


  • Farah Jassawalla

    Farah is a veteran writer, season journalist, and copywriting expert with over six years of professional experience in the content creation field. Her forte lies in translating medical jargon and complicated health terms into easy-to-understand language for readers who may not have a medical background. LinkedIn

  • Kim Monasterial, BSN

    Kim is a Registered Nurse and has been a medical freelance writer for more than six years. Starting off as a writer, Kim moved to proofreading and editing all the articles posted on HealthPlugged. She’s an enthusiast for health and wellness, being one to keep herself fit and adventurous for outdoor activities. LinkedIn


Farah is a veteran writer, season journalist, and copywriting expert with over six years of professional experience in the content creation field. Her forte lies in translating medical jargon and complicated health terms into easy-to-understand language for readers who may not have a medical background. LinkedIn