Time and transit. Ex-lax is a senoside. It is a cathartic (laxative) and promotes peristalsis (movement of content through the bowel). The sooner it goes through, the better off you will be. It is minimally absorbed through the gut. You may have lots of cramps and gushes of diarrhea. If concerned or at risk of other problems due to this, see pcp, call poison control or go to er.