On my first successful flush (after 2 unsuccessful), I woke up at 6 in the morning with bad low blood sugar symptoms including clamminess, rapid heartbeat and weakness. I got to the kitchen and wolfed down an orange and then was okay.
Nothing like this has ever happened to me. This was the standard Dr. Sutter Coke Flush. No epsom salt. My guess is that a slight tendency to hypoglycemia might be exacerbated by stones being ejected from the liver.