The typically recommended dosage of L-Theanine is 100 – 200 mg, although when combined with Caffeine a dosage of 200 mg is more common. There is evidence that exceeding a dosage of 200 mg has little additional benefit, as when more than 200 mg is taken the excess is used by the body as a raw material for protein production.While the standard 200 mg dosage can be exceeded without much risk of adverse side effects, it is generally a waste of money and is not recommended.