It is possible to tell when you are going off the deep end, and therefore take measures to keep from danger (possibly):
Cannot focus eyes for longer than 5 seconds without them rolling back in head; lungs are not functioning properly (taking breaths every 30 or so seconds); vomiting; sudden loss of coordination; fading out of consciousness.
....
So get outside and focus on breathing. This just so you have a better chance of being found during the critical period between respiratory failure and death.
Mostly would agree - in cases of "mild/moderate" overdoses you can often help yourself by walking around if possible, fresh air, people trying to keep communications open with you... If you hit a "serious" overdose you really don't get much say in the matter at all, in my experience - last thing you remember is thinking "Fuck me that was a bit bloody strong!" and the next is being slapped into consciousness after scaring the living crap outta everybody and damn near killing yourself. Anything to try to retain as much consciousness as possible will help but if it's a pretty major overdose you just go down like a sack o' shit within seconds, in my experience.
Also, Nexius

