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  • What Is L-theanine?What Is L-theanine?
  • How Does L-theanine Improve Anxiety?How Does L-theanine Improve Anxiety?
  • L-theanine DosageL-theanine Dosage
  • Warnings & Side EffectsWarnings & Side Effects
  • CBTCBT
  • In My ExperienceIn My Experience
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  • Additional ResourcesAdditional Resources
Anxiety Articles Anxiety Anxiety Treatment Anxiety Types Online Therapy for Anxiety

What Is the L-theanine Dose for Anxiety?

Diana Rangaves, PharmD, RPh

Author: Diana Rangaves, PharmD, RPh

Diana Rangaves, PharmD, RPh

Diana Rangaves PharmD, RPh

Diana Rangaves is an accomplished pharmacist and expert in behavioral health pharmacology. Her areas of expertise include patient education, medication cost-reduction, and patient-centered treatment.

See My Bio Editorial Policy
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Medical Reviewer: Heidi Moawad, MD Licensed medical reviewer

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Heidi Moawad MD

Heidi Moawad, MD is a neurologist with 20+ years of experience focusing on
mental health disorders, behavioral health issues, neurological disease, migraines, pain, stroke, cognitive impairment, multiple sclerosis, and more.

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Published: May 10, 2025
  • What Is L-theanine?What Is L-theanine?
  • How Does L-theanine Improve Anxiety?How Does L-theanine Improve Anxiety?
  • L-theanine DosageL-theanine Dosage
  • Warnings & Side EffectsWarnings & Side Effects
  • CBTCBT
  • In My ExperienceIn My Experience
  • InfographicsInfographics
  • Additional ResourcesAdditional Resources

L-theanine is a natural compound found in green or black tea, which has been promoted for several health benefits, including reducing anxiety symptoms and improving mental focus. L-theanine has been found to have a relaxing and calming effect which helps reduce stress and anxiety.

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What Is L-theanine?

L-theanine is found naturally in tea leaves. This amino acid has been used for its possible health benefits over the past years. Some of the common benefits of this supplement include reducing stress, improving anxiety symptoms, and enhancing cognitive performance. L-theanine was first discovered in 1949 by Japanese scientists who were studying the composition of green tea leaves. The scientists identified the amino acid in tea leaves and its positive effects on the brain. Since then, l-theanine has become the subject of several scientific studies and clinical trials.

This supplement is a popular ingredient in tea-based dietary supplements, mainly green tea leaves. Green tea leaves are a common dietary supplement for many cultures, including Japan, China, and other countries within the Asian continent. For a long time, these Asian cultures have had the tradition of consuming green tea. There are also other sources of l-theanine which include mushrooms and particular species of seaweed.

Potential health benefits of L-theanine include:

  • Reduction of anxiety symptoms
  • Stress relief
  • Enhanced focus
  • Immune system support
  • Improved cognitive performance
  • Better sleep quality

How Does L-theanine Improve Anxiety?

L-theanine has demonstrated various health benefits, notably in reducing stress and anxiety levels.This anxiety supplement may influence several chemical processes and neurotransmitter activities in the brain. Research suggests that L-theanine can modulate cortisol levels and increase alpha brain wave activity, both associated with relaxation and calmness.

Also, l-theanine might influence important neurotransmitter levels such as dopamine and serotonin in the brain, which help regulate mood and anxiety. Dopamine plays an important role in regulating motivation and pleasure, while serotonin influences feelings of calmness and a person’s overall well-being. If L-theanine affects dopamine, you may experience reduced anxiety symptoms and improved mood and energy.

It’s important to note that l-theanine does not cure anxiety but may be used as an anxiety treatment to help relieve symptoms. Therefore, the supplement should not be used as an alternative to therapy or medication prescribed for anxiety. The best thing to do is to consult your doctor to understand the risks and see if it’s safe for you to use this supplement.

L-theanine Dosage for Anxiety

L-theanine is an amino acid found naturally in tea leaves. Sometimes, it is used as a supplement to reduce anxiety symptoms and improve relaxation. The supplement is made from extracts. This is because it would require large amounts of naturally occurring sources to get the same results since the amino acids are naturally low in tea leaves. The recommended daily intake of l-theanine for anxiety is about 200 to 400 mg daily. Ensure you take the dosage as advised by your doctor, as a higher dosage of over 1200 mg can lead to severe side effects.

L-theanine can be combined with other substances to improve its effects on anxiety. This supplement can be combined with substances such as magnesium and omega-3s, essential to improve symptoms of mental illnesses like anxiety. Importantly, consult your doctor before you combine l-theanine with other substances to prevent severe side effects resulting from adverse reactions.

L-theanine is often used in combination with other supplements to help reduce anxiety, such as:

  • GABA: L-theanine and GABA (gamma-aminobutyric acid) have been used together to improve anxiety levels.1
  • N-acetylcysteine (NAC): Both l-theanine and NAC are compounds that might have health benefits for reducing anxiety symptoms.
  • Magnesium: Combining l-theanine and magnesium could potentially reduce anxiety symptoms, resulting in a calming effect.2
  • L-tyrosine: Mixing l-theanine and l-tyrosine may potentially reduce anxiety symptoms by promoting relaxation and calmness.
  • Omega-3s: This is a natural compound that, when combined with l-theanine, helps reduce anxiety levels.

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Warnings & Side Effects of L-theanine

L-theanine is usually recommended to be administered in smaller doses since large quantities of the supplement can cause severe side effects. Also, it’s important to note that while the supplements may be considered safe for use on anxiety, some people are highly discouraged from taking the supplement based on their health condition or age. Certain groups, including children, breastfeeding and pregnant women, and people with preexisting medical conditions such as kidney disease, should not take this supplement without a doctor’s advice. Medications or supplements can adversely react with l-theanine, leading to serious side effects. Therefore, talk with your doctor about the possible side effects of l-theanine with medications.

Possible side effects of L-theanine can include:

  • Mild sedation
  • Nausea
  • Upset stomach
  • Irritability
  • Headaches
  • Dizziness
  • Diarrhea

L-theanine does have the risk of negative interactions such as:

  • Caffeinated supplements: Clinical trials have shown that combining l-theanine with caffeinated supplements improves cognitive performance but can lead to severe headaches.3
  • Antihypertensive medications: L-theanine can interact with medications for high blood pressure, which can cause blood pressure to go slow.
  • Stimulant drugs: Combining l-theanine with stimulant drugs like diethylpropion can make you feel jittery and increase your heartbeat.
  • Sedative medications: The interaction between l-theanine and sedative drugs can cause severe drowsiness and slowed breathing.
  • Selective serotonin reuptake inhibitor (SSRI) drugs: Mixing l-theanine with an SSRI medication can lead to drowsiness or sedation.
  • Alcohol: The interaction between l-theanine with a depressant like alcohol can result in increased drowsiness or sedation.

Cognitive Behavioral Therapy

Cognitive behavioral therapy (CBT) can help with anxiety disorders. A licensed health practitioner can provide this type of psychotherapy in individual or group sessions. CBT is effective at treating anxiety symptoms and other mental illnesses. The primary goal of CBT is to address anxiety by helping people change their thinking and behavior when anxious. This psychotherapy helps individuals interact and change their anxious thoughts, which adds to their anxiety.4

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Anxiety Worksheets

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In My Experience

“L-theanine is an amino acid naturally found in tea leaves that might treat anxiety symptoms. This does not mean the supplement has no side effects, as taking the supplement without following your doctors’ guidance could lead to severe side effects such as drowsiness or sedation. While l-theanine can help with your anxiety, consult your doctor to ensure it’s the right supplement. This helps prevent possible l-theanine interaction with other substances or supplements that can be adverse.”

Diana Rangaves, PharmD, RPh Diana Rangaves, PharmD, RPh

What Is the L-theanine Dose for Anxiety? Infographics

What Is L-theanine   Potential Health Benefits of L-theanine Include

Sources Update History

ChoosingTherapy.com strives to provide our readers with mental health content that is accurate and actionable. We have high standards for what can be cited within our articles. Acceptable sources include government agencies, universities and colleges, scholarly journals, industry and professional associations, and other high-integrity sources of mental health journalism. Learn more by reviewing our full editorial policy.

  • Kim, S., Jo, K., Hong, K.-B., Han, S. H., & Suh, H. J. (2019). GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Pharmaceutical Biology, 57(1), 64–72. Retrieved from https://doi.org/10.1080/13880209.2018.1557698

  • Noah, L., Morel, V., Bertin, C., Pouteau, E., Macian, N., Dualé, C., Pereira, B., & Pickering, G. (2022). Effect of a Combination of Magnesium, B Vitamins, Rhodiola, and Green Tea (L-Theanine) on Chronically Stressed Healthy Individuals—A Randomized, Placebo-Controlled Study. Nutrients, 14(9), 1863. Retrieved from https://doi.org/10.3390/nu14091863

  • 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. Retrieved from  https://doi.org/10.1179/147683010×12611460764840

  • Carpenter, J. K., Andrews, L. A., Witcraft, S. M., Powers, M. B., Smits, J. A. J., & Hofmann, S. G. (2018). Cognitive behavioral therapy for anxiety and related disorders: A meta-analysis of randomized placebo-controlled trials. Depression and Anxiety, 35(6), 502–514. Retrieved from https://doi.org/10.1002/da.22728

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We regularly update the articles on ChoosingTherapy.com to ensure we continue to reflect scientific consensus on the topics we cover, to incorporate new research into our articles, and to better answer our audience’s questions. When our content undergoes a significant revision, we summarize the changes that were made and the date on which they occurred. We also record the authors and medical reviewers who contributed to previous versions of the article. Read more about our editorial policies here.

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Primary Changes: Updated for clarity and readability.
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Primary Changes: Added Anxiety Workbook with nine worksheets.
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