What causes flank pain on both sides?

The flanks are the areas between the upper abdomen and the back. Pain that worsens when you bend, twist, lift, or press the area may come from muscles or joints. Deep pain with fever, chills, nausea, burning urine, frequent urination, or cloudy urine can point toward a urinary infection, including a kidney infection. Kidney stones may cause severe waves of pain, sometimes spreading toward the groin, although stones do not always affect both sides together. Bowel, spinal, or skin-related problems can also be felt in this region.

The timing matters: sudden severe pain, pain after an injury, or discomfort that keeps returning deserves a clinical assessment. A history of urinary infections, stones, pregnancy, or kidney disease changes how promptly you should be checked.

Note when the pain began, whether movement changes it, and any urinary or digestive symptoms. Sip fluids normally unless a clinician has told you to restrict them, and avoid strenuous lifting while the cause is unclear. Do not use leftover antibiotics. A clinician may examine your abdomen and back, check urine, and decide whether blood tests or imaging are appropriate. Treatment depends on the cause rather than the location alone.

Seek urgent medical help for severe or rapidly worsening pain, fever with shaking chills, repeated vomiting, fainting, confusion, blood in the urine, inability to pass urine, or pain after a significant injury. Get prompt assessment if you are pregnant, have one functioning kidney, or feel markedly unwell. These features can signal a problem needing timely treatment, such as a kidney infection or blocked urinary flow.

Ask: Could this be muscular or urinary? Do I need a urine test or imaging? Which pain medicines are suitable for me? What symptoms should make me return urgently?