Theanine is an amino acid found in tea. It is also found in some mushrooms. It is similar in structure to glutamic acid, another amino acid.

Some people take theanine by mouth for anxiety and stress, depression, schizophrenia, for preventing Alzheimer's disease, for treating attention deficit-hyperactivity disorder (ADHD), and improving mental performance and attention. Theanine is also taken by mouth for reducing blood pressure, preventing the flu, and improving how well cancer drugs work as well as decreasing the side effects of cancer drugs.


Is a Form of:

Amino Acid found in tea

Primary Functions:

Anxiety, stress, depression, schizophrenia

Also Known As:

Gamma-ethylamino-L-glutamic acid, Gamma-glutamylethylamide, Gamma-N-ethylglutamine

How Does It Work?

Theanine has a chemical structure very similar to glutamate, a naturally occurring amino acid in the body that helps transmit nerve impulses in the brain. Some of the effects of theanine appear to be similar to glutamate, and some effects seem to block glutamate.


Mental performance. Taking theanine before a test seems to help reduce errors. Taking theanine with caffeine seems to improve a person's ability to switch attention between different tasks.

Recommended Dosing

The following doses have been studied in scientific research:



  • For mental performance: A single dose of 100 mg of theanine before a test has been used. Theanine has also been used in combination with caffeine. Combination doses have ranged from 30-100 mg of caffeine and 12-100 mg of theanine.

Theanine Supplements Frequently Asked Questions

What is the difference between L Theanine and theanine?

Theanine. Theanine, also known as L-theanine, is a non-protein amino acid mainly found naturally in green tea (Camellia sinensis) and some mushrooms (Boletus badius). Theanine is related to glutamine, is speculated to increase levels of GABA, serotonin, and dopamine. Recently, theanine has also been marketed in the US.

Are there any side effects to L Theanine?

Studies have not found side effects from using theanine supplements. Drinking lots of green tea can cause upset stomach and irritability from the caffeine.

Does L theanine help with anxiety?

An amino acid in green tea helps reduce generalized anxiety.

The amino acid L-theanine is an effective treatment of moderate and severe anxiety and does not cause drowsiness.  A calming effect is usually noted within 30 to 40 minutes after L-theanine is taken at a dose of 50 to 200mg, and typically lasts 8 to 10

How long does L Theanine take to kick in?

Calming effects may last 8 to 10 hours and are usually experienced within 30 minutes following ingestion of l-theanine at doses between 50 and 200 mg.

Does L Theanine cause liver damage?

According to a paper from Anhui Agricultural University in China, theanine can protect liver tissue, minimising damage to the liver from chronic inflammation and its resultant diseases. The amino acid was found to increase antioxidant enzyme activity in mice, and to improve the human immune system.

Is L Theanine a muscle relaxer?

BETTER SLEEP - L-Theanine enables the body to produce other calming amino acids, such as dopamine, GABA and Tryptophan and helps with concentration, focus, deep muscle relaxation and improved quality sleep so you feel bullet proof.

Does L Theanine make you sleep?

L-theanine may help people fall asleep more quickly and easily at bedtime, thanks to the relaxation boost it delivers. Research also shows L-theanine can improve the quality of sleep—not by acting as a sedative, but by lowering anxiety and promoting relaxation.

Who should not take L Theanine?

Stay on the safe side and avoid use. Children: Theanine is POSSIBLY SAFE for children when taken by mouth, short-term. Doses of 200 mg of theanine have been safely used twice daily for up to 6 weeks in boys aged 8-12 years. Low blood pressure: Theanine might lower blood pressure.

Does L Theanine make you gain weight?

The anti-anxiety and sleep-promoting abilities of L-theanine may help people to maintain a healthy weight. After all, getting enough sleep and limiting stress are both key to sticking with a healthy diet and avoiding weight gain. L-theanine may also play a more direct role in weight maintenance.

How often should you take L Theanine?

Moderately severe anxiety symptoms may respond to l-theanine taken at a dose of 200 mg twice daily; however, more severe anxiety may require doses up to 600 to 800 mg per day divided into 200-mg increments every 3 to 4 hours.

Can you take L Theanine with Xanax?

No interactions were found between l-theanine and Xanax. This does not necessarily mean no interactions exist. Always consult your healthcare provider.

Can you build tolerance to L Theanine?

Unlike prescription benzodiazepine medications, l-theanine is not habit-forming as it does not lead to tolerance and dependence when used over long periods of time.

Does L Theanine increase serotonin?

L-theanine has been historically reported as a relaxing agent, prompting scientific research on its pharmacology. Animal neurochemistry studies suggest that L-theanine increases brain serotonin, dopamine, GABA levels and has micromolar affinities for AMPA, Kainate and NMDA receptors.

Can theanine cause diarrhea?

Possible Side Effects

To date, little is known about the safety of using L-theanine supplements in the long term. Due to the caffeine content, excessive consumption of green tea may also trigger certain side effects. These may include a headache, insomnia, irritability, diarrhea, and heartburn.

Is L Theanine anti inflammatory?

L-theanine, a water-soluble amino acid isolated from green tea (Camellia sinensis), has anti-inflammatory activity, antioxidative properties, and hepatoprotective effects. However, the anti-allergic effect of L-theanine and its underlying molecular mechanisms have not been elucidated.

Does L Theanine interact with any medications?

Theanine might decrease blood pressure. Taking theanine along with medications for high blood pressure might cause your blood pressure to go too low. Theanine might work to slow down the nervous system. Taking theanine along with stimulant medications might decrease the effectiveness of stimulant medications.

Can you take L Theanine and 5 HTP together?

No interactions were found between 5-HTP and l-theanine. This does not necessarily mean no interactions exist. Always consult your healthcare provider.

Should I take theanine before bed?

L Theanine has been shown to improve sleep quality. It is not a sedative. But it can improve the quality of sleep by reducing anxiety and promoting relaxation as needed to initiate high quality sleep. One study found that 200 mg before bed improved sleep quality and daytime use did not cause drowsiness.

How long does it take for L Theanine and lemon balm to work?

Calming effects may last 8 to 10 hours and are usually experienced within 30 minutes following ingestion of l-theanine at doses between 50 and 200 mg. However, findings of clinical research studies on l-theanine in anxiety are inconsistent.

Does L Theanine make you happy?

L-Theanine Benefits. ... That high L-Theanine makes us feel mentally and emotionally calmer, it helps us focus and improves retention and recall, it also increases dopamine levels so we feel happier!

Clinical Studies