The human digestive system can handle a wide variety of organic and inorganic materials, but occasionally substances such as hair, seeds, pills or vegetable husks become indigestible or partially digestible formations called bezoars. Bezoars can lodge anywhere in the digestive system, but are most commonly found in the stomach, esophagus or upper intestines. Most of these formations are not considered to be life-threatening, but they can cause painful blockages and other digestive problems if not treated or removed promptly. Some bezoars or swallowed foreign objects can also cause intestinal bleeding and an inability to vomit. Some bezoars do require surgical intervention or aggressive drug treatments in order to be removed from the body or rendered harmless.
Many people may be familiar with the feline condition known as hairballs. A cat often ingests a significant amount of hair while grooming, and this hair can accumulate in the animal's stomach until it forms a semi-solid, indigestible ball. The same process can lead to the formation of a bezoar in the human body. A child may habitually chew on the ends of his or her hair, for example. The ingested hair collects in the child's stomach and forms a congealed lump.
As more hair is ingested, other hair bezoars may form or the original will increase in size. A small hairball or bezoar trapped within a child's stomach may not be seen as problematic, but a larger one could migrate towards the stomach's sphincter and become trapped in the upper intestines. Large untreated bezoars can cause a number of digestive problems, including chronic constipation and blood in the stools. Surgical or medicinal intervention may become necessary in order to remove the blockage or break it into digestible pieces.
Some people develop this condition as a result of certain foods. Some vegetable seeds have outer shells which are either indigestible or slow to break down in the stomach. These seeds could collect in the stomach and form troublesome bezoars. Other foods may contain indigestible husks or shells which remain in the stomach long after the food itself has been processed.
One urban legend concerning the lifespan of swallowed gum does contain a kernel of truth; bubblegum and other synthetic gum-based candies can indeed remain in the stomach and form harmful bezoars. This would require swallowing a significant amount of gum, however, and most individual pieces of ingested gum will pass through the rest of the digestive tract without incident.
Some bezoars do appear on traditional x-ray films, along with ingested foreign objects. A child with a large hair bezoar in his or her stomach may need some behavior modification therapy in order to curb the urge to chew on his or her hair, or his or her hair could need to be trimmed in order to prevent future incidents. For bezoars caused by food, a doctor may prescribe medications which soften or dissolve them chemically.
Especially large bezoars may require surgical intervention, either through the abdomen or with instruments introduced through the esophagus. Sometimes a surgeon will physically remove the entire bezoar, while other times he or she will break up the mass into smaller, more digestible parts. Most often, however, the masses will either dissolve over time or pass through the digestive system along with other ingested foods.