Background: Hormonal therapy is a standard treatment for infantile spasms. The high doses given and long treatment duration expose patients to the risk of adrenal insufficiency (AI). This study aims to quantify the incidence of AI among children with infantile spasms treated with corticosteroids and/or adrenocorticotropic hormone (ACTH). Methods: A retrospective chart review of patients treated for infantile spasms was performed between January 2009 to March 2020 in one pediatric specialized hospital. Variables collected included patient and treatment characteristics, risk factors of AI and adrenal function testing. Analysis included descriptive statistics. Results: Thirty-one patients met the inclusion criteria and received a total of 33 separated courses of treatment. Adrenal function following each course of treatment was evaluated in all patients. AI occurred in 25/33 (76% [95CI 58-89]) children. There was no predictive factor of AI. No drug regimen was deemed safe. The two patients (6%) with an acute adrenal crisis were the youngest of the cohort. Conclusions: Adrenal suppression is frequent and can lead to adrenal crisis after standard hormonal therapy for infantile spasms. A routine laboratory assessment of adrenal function should be done for all patients. Hydrocortisone replacement therapy should be given until testing results are obtained, particularly for younger infants.