Pain in both flanks: what to know

Flank pain is felt between the ribs and hips, often toward the sides of the back. Muscle strain may follow lifting, twisting, coughing, or unusual exercise and can worsen with movement or touch. Kidney stones may cause severe waves of pain, nausea, or blood in the urine. A kidney infection may cause flank pain with fever, chills, burning urine, frequent urination, or feeling very unwell. A urinary tract infection can sometimes spread upward.

Note whether the pain is constant or comes in waves, and record fever, urine changes, vomiting, or recent injury. Rest from strenuous activity, drink normally unless a clinician has restricted fluids, and use only pain relief that is safe with your health conditions. Arrange assessment if pain persists, recurs, or has urinary symptoms; testing may include urine checks and other examinations.

Seek urgent care for severe or rapidly worsening pain, fever with shaking chills, repeated vomiting, confusion, faintness, inability to pass urine, or visible blood in the urine. Pregnancy, one functioning kidney, or significant kidney disease lowers the threshold for prompt advice.

Ask whether your symptoms fit a muscle problem, kidney stone, kidney infection, or urinary tract infection; whether urine testing or imaging is needed; and which pain medicines are appropriate for you.