Demerol (meperidine/pethidine) is without a doubt the most painful thing ive snorted. I had some demerol pills and figured since it did not have any APAP or aspirin in it that it would be a good idea to try snorting some. I crushed up 2 of the 50mg pills and since they where very small it was only a small amount of powder. As soon as the demerol hit my nose it felt like someone stuck a blow torch up there. It felt like it was burning a hole right throuh my nose.
I snorted diphenhydraminew once in a effort to make it work faster since i had really bad opiate itches and it burned really bad but not nearly as much as demerol did. Snorting demerol is something you only do once