Prolonged consumption of orlistat causes mainly gastrointestinal adverse reactions, which are related to the pharmacological action of the drug in blocking the absorption of ingested fat. Prolonged use is associated with oily spotting, increased gastrointestinal gas evacuation, urgency of stools, fatty (oily) stools, steatorrhea, increased frequency of stools and fecal incontinence. Orlistat is used for the treatment of obese or overweight patients (body mass index ≥ 24). Orlistat belongs to a group of long-acting and potent esterase inhibitors of the gastrointestinal tract. It exerts its therapeutic effect by binding to the active sites of gastric lipase and pancreatic lipase in the stomach and small intestine, thereby inactivating the enzymes. It is contraindicated in pregnant and lactating women, patients with malabsorption syndrome, cholestasis, and patients with organic obesity (e.g., hypothyroidism). Orlistat reduces the absorption of vitamins A, D, E, K and beta-carotene, and multivitamin supplementation may be considered during treatment. Orlistat should be used under medical supervision, and if the drug has an adverse reaction, it should be stopped immediately and go to a specialized hospital for treatment.