A brown recluse spider (BRS) bite is challenging to confirm, but may be clinically diagnosed by considering the location, the season of the year, and the clinical manifestations. Here, the case of a 26-year-old male who presented after an insect bite with a skin lesion, bruising, severe swelling, and diffuse blisters on the right lower extremity after three days, is described. Following clinical examination, patient history assessment, and consideration of other relevant factors, the patient received a differential diagnosis of necrotizing fasciitis caused by BRS bite. Although spider bite poisoning is rare, proper diagnosis and management are important because, in some cases, the outcomes may be devastating.