How much is too much

I know a few people who have cut back on coffee, or switched to decaf, because of the effect caffeine has on their bodies and minds. But for many coffee-lovers, there just doesn't seem to be a limit on how much they can drink. Or perhaps they just haven't reached their limit. So I wonder what is the limit from a physiological perspective? How much is really too much?

According to an article from the BBC's website, a lethal dose "...for the average person is about 90 milligrams per two pints of blood, according to coffee website Cofcaf.co.uk. This is about 200 cups of instant coffee in a day for an average sized person, it says."

That's a lot of coffee.

Even if not lethal, though, much smaller amounts can cause serious medical problems. The same article reports an overdose of caffeine by a teenager who downed seven double espressos during her work shift at a family sandwich shop, where apparently they serve espresso. She developed a fever and struggled to breathe, heading for shock, not to mention the bizarre behavior she exhibited.

According to her father, she did not know she was drinking double shots. So, let me get this straight. She drank seven espressos, and they think that would have been ok (for a teen), but she didn't know she was getting doubles. There's two things about that that I find interesting. One, drinking seven espressos seems a little over the top to me, especially for a teen, and second, from what I can gather from the article and the accompanying photo, she or someone made the drinks in the family shop, and somehow she didn't realize they were doubles... seven times.