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What You Need to Know About L-Theanine

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Click on an icon to view.Side Effects
There are no known side effects of this product. However, this probably reflects a lack of clinical studies with L-theanine (not a real absence of side effects).(Click L-Theanine Side Effects to learn more, including what to do if you develop a potentially serious side effect.)
L-theanine can interact with a few medications (see L-Theanine Drug Interactions).
Some people may be more likely to experience problems due to this supplement. 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:
- Pregnant or thinking of becoming pregnant (see L-Theanine and Pregnancy)
- Breastfeeding (see L-Theanine and Breastfeeding).
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 L-Theanine Safety for more information, including any available warnings and precautions.)
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD