Allergic contact dermatitis (ACD) after splint or cast application (plaster of Paris) is infrequently encountered in orthopedic and traumatology clinical practice. This case study aims to elucidate the identification of ACD after splint application, highlight the conditions that warrant vigilance, and outline the precautions and optional treatment methods available in such instances. A 56-year-old right-hand dominant female presented to the emergency department after a fall on her right hand, manifesting pain, swelling, and tenderness without neurovascular injury. Radiographs revealed a distal radius fracture, leading to the application of a plaster of Paris splint. Within one day, she returned to the emergency department with severe itching and burning in the right arm. The splint was removed, and a dermatology consultation confirmed ACD due to undercast cotton padding. After splint removal, the patient's fracture treatment continued using a shoulder-arm sling until the lesion healed. Topical antihistamine ointment and oral corticosteroids were prescribed. Regular follow-up revealed the healing and union of the fracture by the fifth week, with minimal residual skin color changes. This case underscores the importance of prompt diagnosis and appropriate treatment in managing such occurrences. A key takeaway is the crucial need to schedule a follow-up appointment with the patient within one day of applying the cast or splint. Skin problems can emerge rather than neurovascular issues following casts or splints. Educating patients on warning signs, including skin irritation, neurovascular deficits, and symptoms of compartment syndrome, ensures the timely identification of significant issues. Healthcare practitioners should inquire about patients' histories of allergic skin reactions, taking a proactive approach to prevent ACD through early intervention and preventive measures.