Flank Pain and Blood in Urine: What to Know

Flank pain is felt between the ribs and the hip, often on one side. Blood may make urine pink, red, or tea-coloured, although it can also be detected only on a urine test. The pain may be sharp and wave-like, or steady and sore. The combination does not identify one cause on its own.

Kidney stones can irritate the urinary tract as they move, causing severe pain that may travel towards the groin, nausea, or visible blood. A kidney infection can cause pain in the side or back with fever, chills, feeling unwell, burning urine, or frequent urination. A urinary tract infection may cause blood alongside bladder symptoms, and infection can sometimes spread upwards.

Other possibilities include inflammation of the prostate, an enlarged prostate, inherited conditions such as sickle cell disease, or less common problems affecting the bladder or kidneys. A symptom does not establish a diagnosis: a clinician may need to examine you and test your urine.

Arrange prompt medical advice, particularly if the blood is visible, the pain is new, or symptoms are returning. A clinician may ask when the pain began, whether it comes in waves, and whether you have fever or urinary changes. Assessment can include a urine test, blood tests, and imaging when appropriate.

Until you are assessed, drink normally unless a clinician has told you to restrict fluids. Do not take leftover antibiotics. Record the urine colour, pain location, associated symptoms, and any medicines you use; this can make the consultation more useful. If you pass a stone, keep it only if a healthcare professional advises you to do so.

Seek urgent medical care if flank pain is severe or rapidly worsening, or if you cannot keep fluids down. Fever, chills, confusion, marked weakness, or feeling faint with urinary symptoms can signal a serious infection. Seek immediate help if you cannot pass urine, are passing clots, or have heavy visible bleeding.

Do not wait for the pain to settle when you have one-sided pain with fever or reduced urine output. An obstructed urinary tract can need rapid treatment, especially when infection may be present.

You could ask: What tests will help identify the source of the bleeding? Could a stone or infection explain the pain pattern? Do I need imaging? Which symptoms should send me to urgent care, and when should the urine be checked again if the blood stops?