Why does urinary tract infection cause flank pain?

A urinary tract infection can cause flank pain when inflammation reaches the upper urinary tract near a kidney. The flank is the area at either side of the back, below the ribs. Infection can irritate tissues around the kidney and stretch the kidney's drainage system, producing an ache, tenderness, or sharper pain in that area.

Flank Pain is a common presentation of Urinary Tract Infection. It is more concerning when it appears alongside burning when passing urine, needing to pass urine often, cloudy or strong-smelling urine, fever, chills, nausea, or vomiting. These features can occur when infection involves the kidney rather than only the bladder. Flank pain also has other possible causes, including a stone, muscle strain, or a problem outside the urinary tract.

The location alone cannot identify the cause. A clinician may check your temperature and abdomen or back, test a urine sample, and decide whether other tests are needed based on your symptoms and examination.

Arrange medical assessment promptly if you have urinary symptoms with new flank pain. Treatment depends on the suspected cause and may include medicine for infection when a clinician considers it appropriate. Take prescribed medicine exactly as directed, and do not save or share antibiotics.

Drink fluids if you can keep them down and have not been told to restrict fluids for a medical reason. Rest may help while you are being assessed. Record when the pain began, which side it affects, urinary changes, fever, and any medicines already taken; these details can help the clinician assess you.

Seek urgent medical care for flank pain with fever or chills, vomiting that prevents you from drinking, confusion, marked weakness, severe or rapidly worsening pain, or trouble passing urine. Urgent assessment is also sensible if you are pregnant, have a weakened immune system, have known kidney disease, or have recently had a urinary procedure.

Go for emergency help if you feel faint, develop severe breathing difficulty, or become difficult to wake. These symptoms need prompt evaluation regardless of the cause of the pain.

Ask whether your symptoms suggest infection in the bladder or upper urinary tract, whether a urine test is needed, and what changes should prompt you to return. If you are given treatment, ask how to take it, what side effects to watch for, and whether follow-up testing is appropriate if symptoms continue.