I was really worried too about cramping. I have pretty bad irritable bowel so it was a concern for me.
I think the first few days I may have felt a few cramps and had looser bm's. Then I was just fine. Actually, my stomach has never felt better! I think the clay slows things down a little.
The cramps I had in the beginning, would not have caused me to miss work or anything. Since there are no herbs in this cleanse, it's pretty easy on you.
Remember to drink lots of water so you don't get backed-up! :-)