A bezoar stone is a solid mass of indigestible material that accumulates inside the gastrointestinal tract, most often the stomach. The word itself comes from the Arabic “bazahr” or “badzehr,” meaning antidote or counter-poison, because for centuries these strange concretions pulled from the guts of goats, deer, and other animals were prized as universal remedies against poisoning.1PubMed. The fascinating history of bezoars Today the term has a split identity: it refers both to a historical curiosity from apothecary cabinets and to a real, sometimes dangerous medical condition that still sends people to emergency rooms.
Why People Once Believed a Stomach Stone Could Save Your Life
The reputation of bezoar stones as miracle cures stretches back to at least the medieval Islamic world and persisted in European medicine well into the 1700s. Physicians and royalty alike paid enormous sums for stones harvested from the stomachs of wild goats, particularly the Persian wild goat, or bezoar ibex. The logic was sympathetic: if the stone formed inside a living body, it must have some life-preserving essence. Bezoar stones were dipped into drinks suspected of being poisoned, worn as amulets, or ground into powder and swallowed outright. Animal bezoars were widely used in medicine until the eighteenth century, when systematic testing began to erode confidence in their powers.2PubMed. The fascinating history of bezoars
Bezoars occupied a peculiar cultural space: part medicine, part luxury object, part spiritual talisman. Their rarity as pathological specimens was a primary reason they were valued, but their supposed properties as antidotes, the spiritual aura surrounding them, and their use in apotropaic (evil-averting) ritual added layers of mystique.3ScienceDirect (Academic Press). Toxicology in the Middle Ages and Renaissance – Chapter 11 – Animal Stones and the Dark Age of Bezoars Wealthy collectors had them set in gold and silver mounts, turning a lump of compressed hair and plant fiber into a piece of decorative art that doubled as emergency medicine. The famous French surgeon Ambroise Paré challenged the bezoar’s reputation in the sixteenth century by testing one on a condemned prisoner who had been given poison; the prisoner died, and Paré declared the stone useless. That experiment did not kill the trade overnight, but it planted a seed of skepticism that grew over the next two centuries.
What Bezoar Stones Actually Are, Medically Speaking
In modern medicine, a bezoar is any tightly packed mass of foreign or indigestible material trapped in the digestive system. Clinicians classify them into four main types based on what the mass is made of: phytobezoars (plant material), trichobezoars (hair), pharmacobezoars (medications), and lactobezoars (milk protein, seen almost exclusively in infants).4PubMed Central. Review of the diagnosis and management of gastrointestinal bezoars Phytobezoars are the most common overall and often form after heavy consumption of certain fruits and vegetables high in fiber, cellulose, or tannins.
Persimmons are the single most notorious cause. They contain high concentrations of tannin, shibuol, and cellulose, which react with stomach acid to form a sticky, hard mass that can grow over weeks or months.5PubMed Central. Persimmon fruit causing simultaneous small bowel and stomach obstruction Other common culprits include celery, pumpkin, grape skins, and sunflower-seed shells. The risk is higher if you eat these foods in large quantities, chew poorly, or have reduced stomach motility for any reason.
Who Gets Bezoars and Why
Bezoars are not random bad luck. Certain conditions make the stomach an ideal environment for a mass to build up. Anything that slows gastric emptying gives food or other material more time to compact. Diabetic gastroparesis, a complication of long-standing diabetes in which the stomach empties sluggishly, is one well-recognized risk factor. It can lead to malnutrition, dehydration, and bezoar formation.6Patient Care. Bezoar Secondary to Diabetic Gastroparesis Previous stomach surgery, especially procedures that alter the shape of the stomach or remove the pyloric valve, also raises the risk substantially because the normal churning and emptying mechanisms are disrupted.
Poor dentition or missing teeth can contribute too: when food is not chewed thoroughly, larger pieces of plant fiber reach the stomach intact and are harder to break down. Elderly patients, people taking medications that slow the gut (certain opioids, anticholinergics), and those with chronic dehydration are all overrepresented in bezoar case reports. Psychiatric conditions play a role in trichobezoars specifically, as discussed below, but for phytobezoars the typical profile is an older adult with a history of stomach surgery or motility problems who eats a lot of fibrous food.
Rapunzel Syndrome and Trichobezoars
Trichobezoars form from swallowed hair and are almost exclusively linked to psychiatric conditions. The chain usually starts with trichotillomania, the compulsive pulling out of one’s own hair, followed by trichophagia, the habit of chewing and swallowing it. Human hair resists digestion entirely. Over months or years, a dense, felt-like mass accumulates in the stomach, sometimes conforming to the stomach’s shape like a cast.7PubMed Central. The rapunzel syndrome: an unusual trichobezoar presentation
In rare cases, the hair mass develops a tail-like extension that trails from the stomach into the small intestine. This is called Rapunzel syndrome, named after the fairy-tale character with impossibly long hair. It is mostly seen in young females with underlying psychiatric illness.8International Journal of Surgery Case Reports. From trichophagia to trichobezoar: Rapunzel syndrome in a child – A case report and literature review Because hair does not dissolve in acid and cannot be broken down by enzymes, trichobezoars almost always require physical removal rather than chemical dissolution. Small ones can sometimes be pulled out endoscopically, but large trichobezoars, which can weigh several pounds, typically need open surgery or laparoscopic extraction.
One reason trichobezoars are medically tricky is that patients often deny or are unaware of the hair-swallowing behavior. Symptoms like vague abdominal pain, nausea, early fullness after eating, and weight loss develop slowly, so the diagnosis may be delayed for months. By the time imaging reveals the mass, it can be enormous.
Pharmacobezoars and Medication Clumps
Pharmacobezoars form when pills or capsules clump together in the stomach or intestines instead of dissolving normally. Extended-release (ER) tablets are especially prone to this problem in overdose situations, because they are designed to release medication slowly and their matrix coatings can fuse together when many tablets are swallowed at once. An in-vitro study found that certain ER tablets formed firm pharmacobezoars that remained stable for more than four hours, with intact fragments persisting up to 24 hours. Drug release from these clumps was reduced by roughly 30 to 50 percent for up to eight hours compared to separated tablets.9PubMed. Potential pharmacobezoar formation of large size extended-release tablets and their dissolution – an in vitro study
This matters for emergency medicine because a pharmacobezoar acts like a slow-release depot of poison sitting inside the gut. Drug levels can spike hours after the initial ingestion, long after clinicians might expect the danger to have passed. In one case involving extended-release carbamazepine and venlafaxine overdose, a pharmacobezoar contributed to bowel ischemia severe enough to require surgical removal of part of the colon. The bezoar may have dissolved or fragmented after whole-bowel irrigation, but persistent drug absorption continued, with drug levels spiking to dangerous concentrations well into the clinical course.10Critical Care Explorations. Functional Pharmacobezoar and Bowel Ischemia Requiring Hemicolectomy Complicating Extended-Release Carbamazepine-Venlafaxine Overdose The takeaway for toxicologists is that standard decontamination strategies may not be enough when ER formulations are involved, and imaging for retained pill masses should be part of the workup.
Complications When a Bezoar Goes Undetected
A small bezoar sitting quietly in the stomach may cause nothing more than mild discomfort or a vague feeling of fullness. But larger ones, or those that migrate from the stomach into the small intestine, can cause serious problems. Bezoars can produce gastric ulcers by eroding the stomach lining through constant pressure and friction. They can also cause intestinal obstruction, perforation, or hemorrhage.11PubMed Central. Phytobezoar: An unusual cause of small bowel obstruction
Small bowel obstruction from a bezoar is a classic surgical emergency. The mass lodges at a narrow point in the intestine, blocks the passage of food and fluid, and causes the bowel upstream to distend painfully. If not treated, the trapped bowel segment can lose its blood supply and die, a condition called ischemic necrosis that requires urgent surgical removal of the affected intestine. Perforation, where the bezoar literally punches through the intestinal wall, spills gut contents into the abdominal cavity and can cause life-threatening peritonitis. These worst-case scenarios are uncommon, but they are real enough that any suspected bezoar warrants imaging and follow-up.
How Bezoars Are Found
Diagnosing a bezoar can be straightforward once a clinician thinks to look for one, but the challenge is that symptoms overlap with many other conditions: gastric ulcers, tumors, bowel obstruction from adhesions, and simple constipation. CT imaging is the gold standard. In one study comparing imaging methods, CT detected bezoars in every patient examined, while ultrasound caught them in most but missed some, and plain abdominal X-rays picked up only a minority. CT was also better at spotting additional bezoars in other parts of the gut that a patient might harbor simultaneously.12PubMed. Gastrointestinal bezoars: sonographic and CT characteristics On a CT scan, a bezoar typically appears as a well-defined intraluminal mass with a mottled or sponge-like pattern that is distinctive once you know what to look for.
Endoscopy, where a camera on a flexible tube is passed into the stomach, can both confirm the diagnosis and begin treatment in the same session. For bezoars stuck in the small intestine, however, endoscopy cannot always reach far enough, and CT becomes the primary tool.
Treatment, Including the Coca-Cola Trick
One of the more surprising findings in gastroenterology is that Coca-Cola is a genuinely effective first-line treatment for stomach phytobezoars. The combination of carbonic acid, phosphoric acid, and the drink’s low pH helps dissolve the sticky tannin-based matrix that holds plant-fiber bezoars together. A systematic review of published cases found that Coca-Cola administration was successful in over 90 percent of phytobezoar cases, either as the sole treatment or combined with subsequent endoscopic techniques. Half of the cases resolved with Coca-Cola alone, and only a handful of patients ultimately needed surgery.13PubMed. Systematic review: Coca-Cola can effectively dissolve gastric phytobezoars as a first-line treatment Phytobezoars made from general plant fiber dissolved more readily than those specifically formed from persimmon tannins, which tend to be harder and more resistant to chemical breakdown.
The typical approach is to have the patient drink Coca-Cola or to deliver it directly into the stomach through a nasogastric tube, then wait several hours or overnight before re-evaluating with endoscopy. If the mass has softened but not fully dissolved, endoscopic tools can finish the job. Endoscopic fragmentation using devices like polypectomy snares, foreign-body forceps, or lithotripsy probes is considered the simplest and most cost-effective approach for gastric bezoars.14PubMed. A giant luminal bezoar treated by mechanical lithotripsy using a yellow zebra guide wire
Enzyme therapy is another conservative option. One case report described a patient with a giant bezoar who completed a three-month course of an oral enzyme complex containing digestive enzymes and probiotic bacteria, resulting in near-complete dissolution without any invasive intervention.15PubMed Central. Successful dissolution of a giant bezoar after enzyme complex therapy This approach demands patience and is only appropriate when the bezoar is not causing an obstruction or other acute complication.
When a bezoar is too large, too hard, or causing an emergency like bowel obstruction, surgery is the answer. Laparoscopic removal has largely replaced open surgery for gastric bezoars, offering shorter recovery times, but the choice depends on the size and location of the mass.16PubMed Central. A modified technique for the laparoscopic management of large gastric bezoars
Bezoars in Animals
Humans are not the only species that forms bezoar-like masses. Horses are particularly prone to enteroliths, which are mineral stones that form in the colon around a small foreign object like a pebble or piece of wire. The mineral in equine enteroliths is typically struvite, a magnesium ammonium phosphate crystal. One analyzed enterolith showed concentric layers of crystal growth outward from a central pebble, with trace elements like iron, manganese, and zinc present at concentrations that matched the ratios found in the horse’s feed.17PubMed. Trace elements in struvite equine enteroliths: Concentration, speciation and influence of diet
Diet plays a major role. Horses fed a high proportion of alfalfa hay are significantly more likely to develop enteroliths, while horses with daily access to pasture grass have lower rates. The working theory is that alfalfa raises the pH and mineral concentration of colonic contents, creating conditions favorable for crystal growth. Reducing alfalfa intake and allowing regular grazing may help prevent the problem.18Journal of Veterinary Internal Medicine. Dietary Risk Factors and Colonic pH and Mineral Concentrations in Horses with Enterolithiasis These equine stones can grow to the size of a bowling ball and cause fatal colic if they obstruct the intestine, making enterolith awareness an important part of horse husbandry in regions like the American Southwest where alfalfa-heavy diets are common.
The historical “bezoar stones” used in medicine were, of course, animal concretions too, typically from the stomachs of ruminants like goats rather than from the colon of horses. But the underlying principle is the same: a foreign or poorly digestible substance serves as a nucleus, and layers of material accumulate around it over time.
What Is Actually Inside a Traditional Goat Bezoar
Modern analytical chemistry has finally answered a question that medieval physicians could only guess at: what are traditional goat bezoar stones made of? A recent study examined the chemical composition of goat bezoars used in traditional Chinese medicine (known as “Houzao”) and found that the medicinally active portion is dominated by ellagic acid, which accounted for roughly 73 to 89 percent of the mass. The remainder consisted of urolithins (gut microbial metabolites of ellagic acid), amino acids, and mineral ash, together accounting for over 90 percent of the composition.19PubMed Central. Quality Analysis of Raw Material and Products of Goat Bezoar Houzao, a Mysterious Traditional Medicine
Ellagic acid is a polyphenol found in many fruits and nuts, including pomegranates, walnuts, and berries. It has documented antioxidant and anti-inflammatory properties in laboratory settings. So the irony is that medieval practitioners were not entirely wrong when they attributed health-promoting qualities to bezoar stones. They were wrong about the mechanism (it was never a magical antidote to arsenic), but the stones did contain bioactive compounds. Whether the concentrations present in a bezoar stone are high enough to produce any meaningful pharmacological effect in a human body is a separate question, and one that modern evidence does not really support for the way bezoars were traditionally used: dipped in wine or scraped into a pinch of powder.
The study also revealed that raw goat bezoar material contains a non-medicinal “stone” portion made largely of minerals and inert fibers, meaning much of the mass of a traditional bezoar is pharmacologically inert. Only the softer, darker layers that form around the core contain the ellagic acid and urolithins. This explains why historical accounts sometimes described bezoar stones as having a layered, onion-like internal structure when cut open, with a chalky center surrounded by darker, resinous-looking rings.
Preventing Bezoars If You Are at Risk
If you have had stomach surgery, have gastroparesis, or take medications known to slow gut motility, a few practical habits reduce bezoar risk. Chew food thoroughly, especially fibrous vegetables and fruits. Avoid eating large quantities of persimmon, celery root, or other high-fiber produce in one sitting. Stay well hydrated, since fluid helps food move through the stomach. If you have had a bezoar before, your doctor may recommend periodic endoscopic checks, because recurrence is not uncommon in people whose underlying risk factors persist.
For trichobezoars, prevention hinges on treating the psychiatric conditions that drive hair pulling and swallowing. Cognitive-behavioral therapy is the most studied approach for trichotillomania, and some patients benefit from medication. Identifying trichophagia early, especially in children and adolescents, is the best way to prevent a mass from forming in the first place. Parents and clinicians who notice bald patches should ask about swallowing behavior, even though the question may feel uncomfortable, because catching it before a mass becomes surgical is far better than catching it after.