A bezoar (BE-zor) is a solid mass of indigestible material that accumulates in your digestive tract, sometimes causing a blockage. Bezoars usually form in the stomach, sometimes in the small intestine or, rarely, the large intestine. They can occur in children and adults.

Bezoars occur most often in people with certain risk factors. You're at higher risk if you:

• Have had gastric surgery that results in delayed stomach emptying
• Have decreased stomach size or reduced stomach acid production
• Have diabetes or end-stage kidney disease
• Receive breathing help with mechanical ventilation

One type of bezoar (trichobezoar) may occur in people with psychiatric illness or developmental disabilities.

Bezoars are classified according to the material that forms them:

• Phytobezoars are composed of indigestible food fibers, such as cellulose. These fibers occur in fruits and vegetables, including celery, pumpkin, prunes, raisins, leeks, beets, persimmons and sunflower-seed shells. Phytobezoars are the most common type of bezoar.
• Trichobezoars are composed of hair or hair-like fibers, such as carpet or clothing fibers. In severe cases, known as "Rapunzel's syndrome," the compacted fibers can fill the stomach with a tail extending into the small intestine. Rapunzel's syndrome is most common in adolescent girls.
• Pharmacobezoars are composed of medications that don't properly dissolve in the digestive tract.

Bezoars can cause lack of appetite, nausea, vomiting, weight loss and a feeling of fullness after eating only a little food. Bezoars can also cause gastric ulcers, intestinal bleeding and obstruction, leading to tissue death (gangrene) in a portion of the digestive tract.

Small bezoars may pass through the digestive tract on their own or after you take medication to help dissolve the mass. Severe cases, especially large trichobezoars, often require surgery.

If you don't have one of the risk factors for bezoars, you're not likely to develop them. If you are at risk, reducing your intake of foods with high amounts of indigestible cellulose may reduce your risk.