I took Avonex for three years and it was a GREAT drug at slowing down the MS. I only quit because the
shot left me feeling like I had the
flu for 3-4 days after the shot. This does not happen to everyone though. Some people claim they have less side-effects after a while on Avonex. Since I was on it for three years, I think I gave it every chance I could. With the Interferons though, you have to have your liver enzymes checked at least every six months. With Copaxone you don't.