Overview

Theanine is an amino acid found in tea and some mushrooms. It comes in two forms: L-theanine and D-theanine. L-theanine is the most common form.

Theanine is similar to glutamate, a naturally occurring amino acid. Glutamate helps transmit nerve impulses in the brain. Theanine sometimes acts like glutamate in the body. But other times it seems to block the effects of glutamate. Theanine might also affect the brain chemicals GABA, dopamine, and serotonin.

People use L-theanine to improve mental function. It is also used for anxiety, mental impairment, stress, and other conditions, but there is no good scientific evidence to support these uses.

Don't confuse theanine with another amino acid called threonine. These are not the same.



Uses & Effectiveness

Possibly Effective for

  • Memory and thinking skills (cognitive function). Taking L-theanine by mouth might help healthy people stay focused. It isn't clear if adding L-theanine to caffeine works better than using either of those ingredients alone.

There is interest in using L-theanine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: L-theanine is possibly safe when used short-term. Doses of up to 900 mg daily have been safely used for 8 weeks. It isn't clear if L-theanine is safe to use for longer periods of time. It might cause mild side effects, such as headache or sleepiness.

Special Precautions and Warnings

When taken by mouth: L-theanine is possibly safe when used short-term. Doses of up to 900 mg daily have been safely used for 8 weeks. It isn't clear if L-theanine is safe to use for longer periods of time. It might cause mild side effects, such as headache or sleepiness.

Pregnancy and breast-feeding: There isn't enough reliable information to know if theanine is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: L-theanine is possibly safe when taken by mouth, short-term. Doses of 400 mg daily have been safely used for up to 6 weeks in males aged 8-12 years.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Medications for high blood pressure (Antihypertensive drugs) interacts with Theanine

    Theanine might lower blood pressure. Taking theanine along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Sedative medications (CNS depressants) interacts with Theanine

    Some medications, called sedatives, can cause sleepiness and slowed breathing. There is some concern that theanine might also cause sleepiness and slowed breathing. But most research hasn't shown this effect. For now, use theanine with caution if you are taking sedative medications.

Dosing

L-theanine is naturally found in tea and some mushrooms. As medicine, L-theanine has most often been used by adults in doses of 200-400 mg by mouth daily for 4-8 weeks. Speak with a healthcare provider to find out what dose might be best for a specific condition.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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