I had the same problem. When I researched it I found 2 scenarios. One is that the Iodine helps rid body of heavy metals. Usually constipation will happen if dumping lead but stool will sink to bottom of toilet not float. Another is that the Iodine kills the good bacteria in your digestive tract so you need to replace that. Sometimes it happens and sometimes not to me, so I think it's the first scenaria in my case.