If you’re a fan of Neil Gaiman’s Sandman graphic novel series, then you might remember reading about bezoars—in particular, trichobezoars, or human hairballs. I’d never heard of such things before and was surprised to learn that humans and other animals, not just cats, can produce hairballs.

Bezoar is a Persian word meaning “antidote,” and it was once thought that bezoars could neutralize poison. Trichobezoars can occur in people who suffer from compulsive hair pulling (trichotillomania) or compulsive eating of non-food items (pica). Trichophagia, or hair eating, is a type of pica. Children or young women manifest these disorders most frequently. Because hair cannot be digested, ingested strands can become twisted and matted as they accumulate in the stomach. Trichobezoars can grow to become quite large, in which case they must be removed surgically. When hair extends past the stomach into the intestines, the condition is referred to as the Rapunzel syndrome.

Online exhibit about hairballs (National Museum of Health and Medicine)
"Hair Apparent: Rapunzel Syndrome" (Case study published in The American Journal of Psychiatry)