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Theanine is a dietary supplement used to treat various conditions, including high blood pressure, anxiety, and Alzheimer's disease. It is an amino acid found in tea that appears to increase serotonin and GABA levels in the brain and protect brain nerves from damage caused by Alzheimer's. At this time, there is not enough scientific evidence to evaluate the safety and effectiveness of these supplements.

What Is Theanine?

Theanine (also known as L-theanine) is an amino acid found in tea. It is also used in dietary supplements and is claimed to be useful for a variety of different conditions, such as anxiety, Alzheimer's disease, and high blood pressure (hypertension).
(Click Benefits of Theanine for more information, including additional uses.)

Are There Side Effects?

There are no known side effects of theanine. However, this probably reflects a lack of clinical studies with the product, not a real absence of side effects.
(Click Theanine Side Effects to learn more, including potentially serious side effects you should report immediately to your healthcare provider.)

Theanine Safety Information

Some people may be more likely to experience problems with theanine than others. Therefore, you should talk with your healthcare provider before taking it if you have:
  • Kidney disease, such as kidney failure (renal failure)
  • Liver disease, such as liver failure, cirrhosis, or hepatitis
  • Any other serious or chronic health condition
  • Any allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
(Click Is Theanine Safe? for more information, including any available warnings and precautions.)
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