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.)
It is not exactly clear how theanine works. It might work for
anxiety by increasing levels of
gamma-aminobutyric acid (
GABA), a brain chemical that is naturally calming. Theanine may also increase serotonin levels in the brain. It is thought that the supplement may also protect nerves in the brain from damage seen in
Alzheimer's disease. In animals, it lowers norepinephrine levels, which may help
lower blood pressure.
There is not yet enough scientific evidence to evaluate the effectiveness of theanine for any use
(see Does L-Theanine Work? for more information).
A safe and effective theanine dose has not been established. Be sure to follow the specific instructions for your particular product.
What If I Take an Overdose of Theanine?
It is not known exactly what to expect from a theanine overdose. If you think you may have taken too much, seek immediate medical attention.
Refer to the label of your individual theanine product for information on how to best store it. Keep this and all other medications or supplements out of the reach of children.
