Glucocorticoids (GC), often used in the treatment of diseases caused by autoimmune mechanisms, are the most common nontraumatic causative factor of femoral head avascular necrosis (FHAN). FHAN is, in turn, the most common cause leading to orthopedic surgery in patients using GCs. As GCs suppress the immune system, patients experience increased susceptibility to infections, including FHAN, which has a similar clinical manifestation with septic arthritis. In rare cases, septic arthritis may be caused by salmonella in patients using GCs. Core decompression is the gold standard in the treatment of early stage FHAN. We report a 28-year-old male patient with multiple sclerosis (MS) presenting with the complaints of hip pain. The patient had been treated with two megadoses of steroids. FHAN was considered due to X-ray and MRI findings. The patient underwent core decompression (CD) and salmonella bacteria growth was found in the hip puncture culture. Avascular necrosis associated with septic arthritis was determined. The patient was re-operated and irrigation and debridement for synovial tissues were performed two days following the first operation. While the association of septic arthritis with causative Salmonella and FHAN is rare except in sickle cell patients, septic arthritis must be considered and ruled out in patients who have previously undergone CD and did not show expected relief in early stage FHAN.