The most recent shot caused fairly obnoxious burning, but still not nearly so obnoxious as some shots in the past. And this was the third shot in the series of 3.
I had doubts about changing from daily 20mg doses of Copaxone to three-times-weekly 40mg doses of Glatopa, the same drug as Copaxone, in the first place, because 20mg x 7 = 140mg total for the week and 40mg x 3 = 120mg for the week, which would mean that, while I would be getting 20mg less of the drug each week, I would be getting twice as much of it each time I injected it.
And in fact there was a fairly steep adaptation in the change from the first version of glatiramer to the second, though I think the reason for that may have been my increasing age and the passage of 10 years from the time when I stopped 20mg daily Copaxone and started 40mg Glatopa 3 times a week.
The steep adaptation involved one mini-episode of something resembling an IPIR, as well as many injection site problems, some so severe that I was awake all night. Most of all, there were episodes of arthritis-like pain in some joint or other, often nowhere near the injection site, that would keep me awake much of the night but disappear some time the next day. These gradually went away after about a year but were hard to tolerate.
"Arthralgia" is listed as a known adverse reaction to glatiramer, and I suspect that that is what these episodes were. "Arthralgia" merely means "pain in a joint" but the pain was severe.
So my thought is that maybe a person taking glatiramer and having problems with it might need to be very careful about timing the injections so as to keep each injection as far apart in time as possible from any other injection, just so as not to be taking in more glatiramer than the body wants the person to have.