I had L-theanine with coffee.. Perhaps i just had too much coffee. The fluctuation i have with caffeine varies a lot! As i sometimes have a lot of coffee and other days little coffee. Today i had a lot of coffee and quite a bit of L-theanine about 300mg. I was around people i am comfortable to speak with. I spoke pretty smoothly. I suggest to give it a try! I'm going to take some notes an experiment a little more without coffee and post about it here soon! Like i said i worked as a cashier and that is definitely an anxiety filled situation for a stutterer. It might have been coffee+anxiety that made it worse... L-theanine is kind of on the easy side of calmness. Perhaps if i took a really high dose? I'm not sure what those effects are long term though.