I have taken L theanine 200mg for well over a year, also for anxiety. It really does help and I've had no negative side effects. It works gradually, not like a benzo...and you need to take it every day to keep it in your system. I take mine now at night with 2mg melatonin for sleep, but have taken it during the day as well and it won't make you groggy. Best of luck to you, dealing with anxiety is awful!