People seem to react differently to Ivig. I do three days every 4 weeks. I finished my 2nd round yesterday. I experienced no side effects at all during/after days 1 & 2. Toward the end of day 3 and throughout day 4 (today) I get a mild headache and some stomach discomfort. Yogurt, Ginger Ale and Mylanta work well. The headache will probably disappear today. The stomach issue may last a few more days. The side effects have decreased this time