Pain on both sides of the waist may be caused by kidney diseases such as pyelonephritis, kidney stones, etc. It may also be caused by lumbar muscle strain. 1. Pyelonephritis: Pyelonephritis belongs to upper urinary tract infection, the inflammation on the renal pelvis localized stimulation may cause low back pain, if bilateral pyelonephritis can lead to both sides of the pain discomfort. 2. Kidney stones: patients with kidney stones may cause obstruction of the renal pelvis outlet, the urine produced by the kidneys accumulates in the kidneys to form hydronephrosis, more and more water accumulates in the kidneys, the pressure in the renal pelvis is getting higher and higher, and the patients may have the symptom of pain on both sides of the waist. 3. Lumbar muscle strain: pain on both sides of the waist is not necessarily caused by kidney disease, patients with lumbar muscle strain will cause muscle contracture, local muscle anaerobic metabolism, lactic acid increase may also lead to pain on both sides of the waist, overworked waist pain may worsen. Pain on both sides of the waist may also have other reasons, it is recommended that patients go to the regular hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.