[nick__m]

It is quite uncommon and usually doesn't devolves into a life destroying situation but it exist :

   The first published report of caffeinism — essentially an anxiety disorder based on chronic high caffeine consumption — appeared in 1967 and described the case of a woman thought to have an anxiety disorder until it was determined that she was consuming 15 to 18 cups of brewed coffee per day. She showed rapid improvement when her caffeine intake was drastically reduced.

https://www.pharmacologicalsciences.us/caffeine/ccaffeinism....

[tehjoker]

I will say that I didn't read the directions on some new freeze dried instant coffee I got and was accidentally brewing 2x the recommended concentration and felt like I was losing my mind for months until I figured it out.

[ihumanable]

I didn't start drinking coffee until well into my 20s, just never developed a taste for it.

One day after I had started drinking coffee a friend wanted to go to Starbucks. They were excited that I finally started drinking coffee and we could go for a walk and grab a cup. I had heard Starbucks was pretty awful coffee but the coffee was a side point, so I went and got a cup of coffee.

I was wildly caffeinated the rest of the day. My brain had made an incorrect association that "awful coffee" == "weak coffee" so I got the largest one because I was a bit tired. That was WAY TOO MUCH caffeine, a Venti coffee at Starbucks has 225mg of caffeine and the standard cup I was brewing at home / in the office was closer to 90mg.

That was a difficult afternoon at work, unable to sit still, agitated, but I learned a good lesson. Starbucks didn't get rich from flavor, they did it the old fashioned way, massive quantities of addictive substances, caffeine and sugar.