I started having reactions after a year of taking it successfully. It started about
10 minutes in to an infusion and all of a sudden I got really hot and felt like I was on fire from the chest up. I thought I was going to pass out, so I told the nurse and she stopped the infusion. Immediately, I had to go to the bathroom. Dr. confirmed it was a reaction and said I couldn't continue that treatment. Eventually tried premedicating first, going to the hospital as outpatient and getting the infusion over a slightly longer period of time, etc. but nothing worked. Last resort was being in the hospital for 23 hours and had the infusion over 19 hours. I almost had the reaction but it calmed down and I was able to get the treatment. But, by then the antibodies made it not work very well and I decided it wasn't work the hospital stay every 6 weeks. But, my reactions were always within 15 minutes of starting the infusion (except for the 19 hour infusion), so I knew pretty quickly in. And, they always got better once the infusion was stopped. Good luck...I hope you don't have any problems.