Severe left flank pain: causes and next steps

The flank is the area between the ribs and hip, beside the spine. Pain from a Kidney Stone may come in waves and spread towards the groin; a Kidney Infection can cause flank pain with fever, chills, nausea or feeling unwell. Urinary Tract Infection symptoms may include burning urine, urgency or cloudy urine, although flank pain can have non-urinary causes such as muscle irritation. Location alone cannot identify the cause.

Arrange medical advice promptly if pain is severe, lasts, returns, or comes with urinary changes. Note its onset, wave-like or constant pattern, movement, fever, vomiting, urine colour and any injury. Sip fluids if you can keep them down, but do not force large amounts if vomiting or if a clinician has advised fluid restriction. Avoid driving while pain or medication affects concentration.

Seek urgent care for flank pain with fever or chills, repeated vomiting, inability to pass urine, blood in the urine, fainting, confusion, severe weakness, or rapidly worsening pain. Pregnancy, one functioning kidney, known kidney disease or recent injury lowers the threshold for prompt assessment.

Could this be urinary, muscular or another type of pain? Do I need urine testing or imaging? Which pain medicines are suitable for me? What changes should send me to urgent care?