Posted 10/5/2015 11:40 AM (GMT -6)
They start out as different chemicals but after metabolic processing the chemical is identical. Imuran breaks down into 6mp.
It might be important to distinguish side effect, from allergy, form intolerance. All of these can suck, but each has different implications.
A side effect might be managed with dosing, food, or additional drugs. Allergy will involve antigens, might also be managed with something like an antihistamine.
Intolerance means all management options failed.
I see you report Mesalamine intolerant. BE careful about concluding 6mp intolerance too quick, because you can run out of drug options.