Anti-seizure medication (ASM) can effectively control epileptic seizures but can also convey side effects, which are pharmacological effects that coexist with the targeted effects of ASMs. There is no drug that does not carry a possibility of side effects. However, some side effects are acceptable, while others can cause fatal harm to patients and are not acceptable. Therefore, based on the degree of damage to the patient, some side effects of ASMs can be divided into fatal side effects, such as fatal epidermolysis, hypersensitivity syndrome, cardiac arrest, and sudden death. Some ASMs do not cause death but have serious effects on the patient and their offspring, such as birth malformation, mental abnormalities, metabolic encephalopathy, and malignant hyperthermia syndrome. Some side effects, such as weight gain, nausea, and hair growth, are acceptable. Clinicians should be highly concerned about fatal side effects and should do their best to avoid them.