It is possible for a small amount of arachnoid hemorrhage to cause epilepsy after it has healed, and epilepsy can occur in the acute phase or in the recovery phase. The results of studies related to seizures after subarachnoid hemorrhage show that the incidence of epilepsy after subarachnoid hemorrhage is 6% to 20%, which can occur in the acute phase of subarachnoid hemorrhage or in the recovery phase. Acute-phase seizures are associated with mechanical stimuli such as increased intracranial pressure from cerebral edema or ischemic stimuli resulting in rapidly intensified, enlarged, and synchronized cerebral neuronal discharges that cause seizures. Late-onset seizures may be due to neuronal degeneration, reactive abnormal astrocyte proliferation, glial scar formation, and cystic cavity formation that form epileptic foci leading to seizures. However, not all patients with subarachnoid hemorrhage develop seizures. Generally, anticonvulsant drugs can be used prophylactically in the early stage after subarachnoid hemorrhage. Long-term use of anticonvulsant drugs is not recommended, but long-term use of antiepileptic drugs can be considered if the patient has a history of seizures, cerebral hemorrhage, and other risk factors.