Phenobarbital is a central depressant drug, which is used in different doses and has different effects. Patients need to take phenobarbital in different doses due to their clinical symptoms. From small to large doses, the effects of phenobarbital are sedative, hypnotic, anticonvulsant, and anesthetic in order of magnitude, with the smallest dose required for sedation, usually 10-20 mg/dose, 3 times a day. Excessive doses of phenobarbital can cause respiratory depression, which may result in serious consequences if not resuscitated in time. Therefore, patients should strictly follow the doctor’s prescription in clinical practice, and it is forbidden to change the dose without authorization.