You IV-d Codeine?? Thats a very silly thing to do, I suppose u learnt from ur mistakes. Im not surprised about the adverse reaction and histamine release etc etc. IM isnt safer either. Not sure why people assume it is safer. Good thing that ur still alive which is the main thing.
IM codeine is safe, and has been used for a long time in medical settings. Unless of course you meant IM'ing pills that contain codeine, then that's not safe as it's likely to give you an abcess.
Of course, as everyone here knows, IVing medical grade codeine can be deadly, don't do it.