When a person swallows dental floss, the body usually does not have any problems, and the dental floss passes through undigested, states ZocDoc. On rare occasions, it causes a blockage in the stomach or intestines or causes two loops of bowel to become stuck together.
Symptoms of a blocked GI tract are nausea, discomfort, abdominal swelling and the inability to pass gas or stool, advises ZocDoc. This is a serious condition that may require surgical intervention. If the dental floss gets caught and ties two bowel loops together, they may become fused, resulting in a serious condition that also may require surgery to correct.