The aim of this study was to report a clinical case of extravasation of 1% sodium hypochlorite into the periapical tissues during endodontic treatment. During apical debridement, absence of reflux of the irrigating solution was observed, followed by root canal hemorrhage. The patient immediately complained of intense pain, and a profuse edema and hyperemia was observed on the left side of her face compatible with extravasation of hypochlorite to the periapex. The patient was treated with ibuprofen 600 mg three times per day for three days, a single dose of dexamethasone 4 mg, amoxicillin 500 mg three times per day for seven days, and a cold compress for two days. Regression of the condition began on the fourth day, and normal tissue aspect and absence of sequelae were observed on the 14th day.