What should you know about back and flank pain?

Flank pain is felt between the ribs and the hip, often on one side. A strained muscle may hurt with movement, lifting or pressing the area. Kidney stones can cause intense waves of pain that travel towards the groin, sometimes with nausea or blood in the urine. Kidney infection may bring a steady flank ache with fever, shivering, nausea or painful urination.

A urinary tract infection can cause burning or frequent urination and may spread upwards. Pain that follows an injury, affects both sides, or comes with numbness may have a different source. These patterns overlap, so pain location alone cannot identify the cause.

For mild pain after activity, reduce the aggravating movement, keep gently mobile, and use a wrapped heat or cold pack for short periods. Drink normally unless a clinician has advised fluid restriction. Note the side, onset, movement triggers, urinary changes, fever and any blood in urine.

Use pain medicine only as directed and check with a pharmacist if you have kidney disease, stomach ulcers, take blood thinners, or are pregnant. Do not ignore urinary symptoms that accompany flank pain. See [Flank Pain](/symptoms/flank-pain/) for more context.

Get urgent medical assessment for severe or rapidly worsening pain, fever with flank pain, repeated vomiting, blood in urine, inability to pass urine, fainting, or pain after a significant injury. New leg weakness, loss of bladder or bowel control, or numbness around the groin needs emergency care.

Arrange a same-day review when pain comes with burning urination or chills, because a kidney infection or urinary tract infection may need prompt treatment. Seek advice if mild pain persists or keeps returning.

Could this be muscular or urinary pain? Do I need a urine test or imaging? Which pain medicines are suitable for me? What changes should send me to urgent care? How can I reduce the chance of recurrence?