title_body: How to weaken effects of caffeine after consumption
upvoted_answer: What you experienced was a caffeine overdose, however mild, and that's something that you shouldn't really try home remedies to correct. Had you gone to the emergency room, you probably could have expected to been given a laxative, activated charcoal, and possibly I.V. fluids. I doubt that they would have pumped your stomach over a single cup, but they might have if your heart was beating irregularly. 
  
  Absorption of most things you swallow generally depends on how much you've had to eat - so yes, eating something filling (e.g. bread soaked in water) would probably have alleviated some of the discomfort, especially if you had the coffee on an empty stomach. Staying hydrated (but not over-hydrated) would also have been important. 
  
  I wouldn't advise self-medicating in circumstances like this, all you can do is be very mindful of symptoms getting worse (particularly any sign of irregular heart activity) while you wait it out and (eventually) crash into bed. 
  
  But, bread / crackers / water - not going to hurt, and might make you feel a little better, or better sooner. While symptomatic, I wouldn't take anything over the counter or prescription unless you checked with a doctor (because of possible heart implications)
  
  And really, if you feel at all beyond 'blaugh' - you should see a doctor quickly. People die from too much caffeine, and it's not pretty, so be careful.