So after my gastroenterologist visit I was given stuff to do to “clean me out” Gastroenterologist visit. This is the same kind of prep for a colonoscopy. I had to take magnesium citrate and I was so nervous about having an accident. I took it and waited, and waited, and waited. This is supposed to work within 30 minutes to 3 hours. Eight hours later nothing. Finally the following morning I went a little, far from the “cleaned out” goal….