Just looked up the side effects - they sound very similar to what happens when you go for a run (heavy breathing, wheezing, sweating, dry mouth, etc)! Maybe I don;t have asthma, maybe I should just stop running!
Flat coke is the best thing for a late-race perk up, and even better for the hangover the following day
Breakfast before a long race (mara/IM/etc) is usually a tin of rice pudding, and maybe a bit of bacon. Never bother with coffee due to the laxative effects mentioned previously, which only ever seem to kick in just at the start line before the gun goes.
Training-wise, sometimes I eat before a long run, sometimes I don't. I have plenty of internal energy reserves that come with me, so if i forget to eat something else it's probably for the best anyway...