"Arthralgia (from Greek arthro-, joint + -algos, pain) literally means joint pain; [1][2] it is a symptom of injury, infection, illnesses -- in particular arthritis-- or an allergic reaction to medication."

Since Avonex has this as a side-effect, that is most likely the cause. From what I've heard, many of the side-effects from interferons will let up in time for most people.

I had an allergic reaction to Tetracycline when I tried it, and ALL my joints hurt and became stiff. I was taken off that medication and told it was a very rare allergic reaction.

Just something to keep in mind . . .

Cherie