I agree with the others - Brand is Key... I was on one brand (can't remember the name) and had all the bad reactions.. once they switched to Gammunex I have been SOOO much better.. The infusion nurses basically say some of the brands are "dirtier"/ have more by products that can cause ill effects, while the Gammunex is "cleaner".. and causes fewer reactions.. How are you feeling? what did the neuro say?