Fatigue is a major symptom of MS. I've been on betaseron for over 10 years and never found it (per say) to cause fatigue the day of or day after shooting up. The MS fatigue is a different story. Early in my diagnosis, first year on beta, fatigue was a HUGE problem--along with all the fears, concerns, unknown symptoms, having to self inject, blah blah blah. They didn't have "starter dosing" in 2000, was at "the dose" from day one and that never has been a problem. still have chills/body aches about 50% of the time I take it, but tylenol/ibuphrophen take care of that.

I explored options to help with the fatigue and found something that worked for me. I'm sure if you peruse the boards, there are many suggestions for helping with fatigue.