I was on Avonex for three years and recently switched to Copaxone. One of the side effects of Avonex in my case was to make my MS symptoms worse about 5 days out of 7. My neuro indicated that for some people Avonex does indeed make MS symptoms worse.
Subsequently I learned "spasticity" is a pretty common side effect of interferons. In my case, the knots in my hamstrings, instead of disappearing on day 5 or 6 after each Avonex injection, totally disappeared once I switched meds.
Of course, I don't actually know that Avonex was the contributing factor, but I sure do think so. I've found the relief to be pretty remarkable.
Now, I've got my fair share of lumps from the Copaxone
but I'll take them any day compared to what I was experiencing.