If a patient has fever and kidney pain, he or she most likely has acute pyelonephritis. Acute pyelonephritis is a type of urinary tract infection, which belongs to the upper urinary tract and is a more serious urinary tract infection. When bacteria infect the renal pelvis, local inflammation occurs and stimulates kidney pain, along with fever. Some patients may also have chills before the attack. If the infection is complicated by acute cystitis, it may be accompanied by frequent, urgent, and painful urination. Although the onset of acute pyelonephritis is rapid and the symptoms are severe, most of the disease improves with anti-infective treatment. The best antibiotics for this infection are cephalosporins, penicillins, and quinolones, such as ceftriaxone, sodium penicillin for injection, and moxifloxacin. During the anti-infection treatment, you must pay attention to drink more water and urinate regularly, which can promote the healing of the disease.