Yes, makes mine worse, so I’ve cut caffeine out completely and I’ve improved. Caffeine causes a surge in dopamine and narrows blood vessels in the brain. Not good for most stutterers. Some benefit from it, but some don’t. It’s an imbalance of neurotransmitters in our brain. If someone has too low dopamine, caffeine might push the levels up into the goldilocks zone and improve fluency. But if someone has too high dopamine baseline levels, causing a surge will make it even worse. I fall into the latter camp. Caffeine makes mine worse!