Swallowing a magnet the size of a watch battery is unlikely to cause health problems, but swallowing two can be fatal.

Braden Eberle, 4, of San Jose, Calif., told his mother that he had swallowed something, a tiny magnet attached to a toy. His mother assumed that it would pass through. The next day, his parents saw him swallow another.

Image STUCK X-ray shows magnets a boy swallowed on separate occasions. Credit... JAMA

Within 72 hours, Braden complained of mild pain in the left abdomen. He had no other symptoms and was not in any apparent distress, but his parents took him to the emergency room anyway. An X-ray showed what Dr. Sanjeev Dutta, in a case study published on Feb. 4 in The Archives of Pediatrics and Adolescent Medicine, calls “an obvious opacity in the right lower quadrant area of the cecum,” a foreign object near the mouth of the large intestine.