Small household magnets, like the ones on your refrigerator door or used as toys, can be very dangerous if swallowed. According to UC Davis Health, if these magnets are swallowed, they can become attached together inside the body. When that happens, they can create fistulas, which are abnormal connections within the body, or even holes in the intestine.
The National Capital Poison Center reports that, in 2019, almost 1,600 cases of magnet ingestion were reported to the U.S. Poison Control Centers. Additionally, there were 1,700 hospital visits between 2009 and 2011 due to people, mostly children, swallowing magnets. In some cases, surgery was required to remove the magnets; in one instance, the child did not survive. In the cases of the children who did survive, many of them suffered permanent damage to the digestive tract. This is in part because, when the magnets join together or a single magnet joins with another metal object that a child may have swallowed, it can cut off the blood supply to that area, leading to tissue death.