There is limited knowledge on amphibian sedation, and drug doses appear to be species-specific and affected by the administration route. Alfaxalone, a neuroactive steroid, has gained popularity in veterinary medicine and has been evaluated in some amphibian species. Previous studies in amphibians have demonstrated a sedative dose range of 10–30 mg/kg IM. No peer–reviewed publication has investigated this drug in Sonoran Desert toads (Incilius alvarius) specifically. Therefore, the purposes of this study were 1) to determine the effective dose 50 (ED₅₀) of IM alfaxalone for sedation, and 2) to determine the cardiopulmonary effects of the effective dose 99 (ED₉₉) in 13 Sonoran Desert toads. Using Dixon's up-and-down method, the ED₅₀ was calculated as 9.02 mg/kg, and using a nonlinear regression, the calculated ED₅₀ was 9.65 mg/kg, and the ED₉₉ was 9.91 mg/kg. Based on these results, 10 mg/kg IM was administered, and its cardiovascular effects were determined for 120 min postinjection. The 10 mg/kg IM dose resulted in significant transient cardiorespiratory depression in all toads, with most toads (11/13) showing signs of sedation (recumbency and/or loss of righting reflex) within 30–40 min postinjection. There was no associated mortality with this study, and the side effects associated with this dosage (cardiorespiratory depression, ventral erythema, and dysphoric behavior such as rolling and head pressing) resolved in all toads prior to the end of the 120 min observation window. This study hopes to increase the understanding of the clinical application and limitations of this drug for sedation of Sonoran Desert toads.