What should you know about pulsating flank pain?

The flank is the area between the ribs and hip, on either side of the back. A rhythmic or throbbing feeling may reflect muscle spasm, irritation around the spine, or pain referred from the kidney or urinary tract. Kidney stones can cause intense waves of pain that move toward the groin. A kidney infection may cause flank pain with fever, chills, nausea, or urinary symptoms. The location alone cannot identify the cause, so timing, movement, urine changes, and other symptoms matter.

Note when the pain began, whether it comes in waves, and whether movement or pressure changes it. Drink normally unless a clinician has advised fluid restriction, and avoid strenuous lifting until the cause is clearer. Do not use another person’s prescription medicine. Arrange medical advice for pain that persists, recurs, or occurs with burning urination, frequent urination, blood in the urine, nausea, or fever. Related information is available under Flank Pain, Kidney Stones, Kidney Infection, and Urinary Tract Infection.

Seek urgent medical care for severe or rapidly worsening pain, fever with flank pain, repeated vomiting, faintness, confusion, or difficulty passing urine. Emergency help is needed if you feel very unwell, become weak or drowsy, or develop severe pain with a single functioning kidney, pregnancy, or a known urinary blockage. Do not wait for the pain to settle when these warning signs are present.

Ask whether your symptoms fit a kidney, urinary, muscle, or nerve problem; whether urine testing or imaging is needed; and which pain treatments are suitable for you. Ask what changes should prompt immediate review.