I had about 9 or 10 IVIG infusions last year for Autoimmune Encephalitis. They worked quite well, and no side effects--- BUT:
I must warn anyone who does decide to take them that they are outrageously expensive, each session cost approx. $17,000, so you best thoroughly discuss with your dr. and your insurance company, and the facility giving the infusions.
The reason for the terrible expense is the cost of the globulin.