Left flank pain radiating to the back

A kidney stone can cause severe, cramping pain that shifts from the flank toward the lower abdomen or groin. Kidney infection may cause a deeper back or flank ache together with fever, chills, nausea, or feeling unwell. A urinary tract infection may add burning, urgency, or frequent urination. Muscular pain is more likely to vary with bending, lifting, twisting, or pressure, while spinal irritation may follow a line and include tingling or weakness. Pain spreading to the upper abdomen, chest, or shoulder has a different urgency and should be described clearly.

Write down where the pain starts, where it travels, how long each episode lasts, and what changes it. Avoid heavy lifting until the cause is clearer, keep normal fluid intake unless medically restricted, and use appropriate pain relief as directed. Seek a clinical review if the pain continues, repeatedly returns, or comes with urinary or systemic symptoms. A clinician may check your back and abdomen and test urine.

Seek urgent care for sudden severe pain, fever with flank pain, persistent vomiting, weakness or numbness, fainting, confusion, blood in urine, inability to urinate, or pain after trauma. New chest pain or breathing difficulty also needs emergency attention.

Ask whether the radiation pattern suggests a kidney, muscle, or spine problem, whether testing is needed, and which changes require immediate help. Share any fever, urinary change, bowel symptom, rash, numbness, or recent exertion.