I usually drink one cup of coffee every day with a meal, and often experience some mild anxiety. But today I took 100 mg caffeine powder (which I thought would be equivalent to one cup of coffee) this morning with breakfast, which made me a little anxious. Then with lunch a cup of coffee. I guess it was the coffee on top of the caffeine powder already in my system that threw me into a horrible anxiety state that came on gradually after lunch and just got worse over the next 7 hours. I just took some activated charcoal because it was so bad. I definitely won't be taking that much caffeine again anytime soon. :?