Is Theanine Bad for You?

Health Effects

According to, theanine is used to relieve stress and it has a relaxing effect without causing drowsiness. This amino acid may boost the body's immune system and fight infections.

Food Uses

A synthetic version of L-theanine is added to many food products in Japan including chocolate, herb teas and soft drinks.

Other Uses

L-theanine has been added to cosmetics because of its moisturizing effect on the skin.


Theanine use has not been studied in pregnant women and breastfeeding mothers. Women who are nursing or pregnant should discuss theanine use with a doctor.

Negative Effects

Side effects have not been reported with L-theanine consumption and this amino acid has not been found to be toxic to humans.