Hi there, I'm not sure how long ago this was posted, but I thought I would respond just in case someone might see it. Yesterday for the first time I took some systemic enzymes. Within the first hour I felt great...but a couple hours later I started to feel really sick, and as the day and night wore on it got worse and worse. I ended up feeling like I had a truly terrible flu-bug: chills, aches, bed-ridden. Even today, I am recovering from this experience. SO is it die-off? Or an intolerance? My reaction was so severe I don't think I should try them again!