Ceftriaxone is a third-generation cephalosporin commonly used in serious gram-negative infections, due to broad spectrum against bacteria, long half-life, and easy to penetrate into the cerebrospinal fluid. Neurological adverse effects resulted from cephalosporins include wide ranges of clinical manifestations, such as a change in mental status or encephalopathy, and seizures. This case is a 74-year-old woman, which 10 days use of ceftriaxone with induced encephalopathy and seizures, state of consciousness was recovered and seizures were under control 6 days after discontinuation of ceftriaxone. According to the literature, the neurological adverse reactions caused by ceftriaxone were highly suspected. This case reminds medical professionals to be aware of unusual behaviors followed by ceftriaxone use, in order to reduce the possible damage caused by adverse reactions.