Just recently, the BBC reported about a girl who was taken to hospital after a coffee overdose. They have since followed this up with some health advice on How much is too much coffee?.

This reminds me of 3 things.
1. I had a good friend at university who was renowned for eating instant coffee straight from the jar in order to stay awake during lectures. I never witnessed this and cannot comment on the truth of this story, but I guess it’s a good way to get the coffee into you.
2. A further friend was staying with her relatives for Shabbat. She had been out and about in the morning and, wherever she happened to be, they were giving out free ice coffee. She had several of these free ice coffees, got to her relatives and then buzzed around, cleaning and washing the floors before Shabbat, until the caffeine buzz wore off.
3. The same friend was so desperate to have a particular fizzy drink after Pesach (Passover), that she drank an entire bottle of the stuff. She didn’t realise at the time that it contained caffeine, and wondered why she could not get to sleep until the early hours of the following morning.

This just goes to show that you can have too much of a good thing.