A 77-year-old male patient received an Ⅳ infusion of tigecycline 100 mg for the acute exacerbation of chronic obstructive pulmonary disease and the flora species being sensitive to tigecycline in his antibiotic sensitivity test.About 3 hours after the infusion,the patient developed mental and behavioral abnormalities such as hallucinations and balderdash.Tigecycline was stopped the next day,and the patient's consciousness improved and he could answer questions correctly.Because of the poor control of the infection,an Ⅳ infusion of tigecycline 50 mg was given 6 days later.About 8 hours after the infusion,the patient developed mental and behavioral abnormalities such as staring at a certain place and unresponsiveness to verbal stimuli.Then tigecycline was stopped,and the patient's consciousness recovered.