What Is L-Theanine?

L-theanine is an amino acid found naturally in black tea and green tea. It's also available as an over-the-counter supplement. L-theanine supplements can be purchased in a variety of formats, including tablets, liquids, powders, and capsules.

Ingesting L-theanine when you drink tea is safe. However, it's important to talk to your healthcare provider before you start taking any new supplement, including L-theanine. The dosage is much higher in supplement form, and it's important to discuss whether L-theanine could have potential interactions with any of the medications you take. For example, antidepressants and blood pressure medications may interact with LL-theanine. Some of the people who are advised against using L-theanine supplements include pregnant and breastfeeding women, children, and people with certain pre-existing medical conditions.