Glucomannan is a dietary fiber that is the main polysaccharide obtained from the tubers of the Amorphophallus konjac plant. It has been used as a dietary fiber for more than 1,000 years in eastern cultures, and has gained popularity in many western countries over the last 20 years. This soluble fiber has very substantial water-holding properties, and forms highly viscous solutions when dissolved in water. It also has considerable hygroscopic properties, expanding rapidly to many times the size of the original material. These properties have made glucomannan an ideal diet agent as the material swells in the GI tract after ingestion, producing a feeling of satiety and fullness. It has also been reported to have hypocholesterolemic, hypoglycemic, hypoinsulinemic and anti-constipatory effects. The negative effects reported include flatulence, abdominal pain, gastrointestinal obstruction, and possible modification of the bioavailability of other medications. This report describes a 37-year-old female who developed delayed esophageal obstruction after ingesting an over-the-counter diet aid containing glucomannan. The patient ultimately cleared the obstruction through forceful emesis, just prior to upper gastrointestinal endoscopy. The patient was noted to have an esophageal web during outpatient endoscopy. This case illustrates the potential dangers of glucomannan and other hygroscopic medications in patients with a history of upper gastrointestinal pathology.