Lower Back / Flank Pain
Kidney & UrinaryKidney cancer. Aortic aneurysm. Spinal tumor. Renal artery stenosis.
Muscle strain (most common cause of lower back pain overall). Kidney stones passing through the ureter (this one actually hurts — intensely — and is very distinctive). UTI with kidney involvement (pyelonephritis). Poor posture. Constipation pressing on back structures.
🧠 The full picture
True kidney pain is felt in the flank — the area between the last rib and the hip, usually on one side. It often radiates into the lower abdomen or groin. It's distinct from muscular back pain, which is usually bilateral and mechanical (hurts more with movement).
⚠️ When to actually call your doctor
These are real red flags. If any of these apply, don't wait.
- Severe one-sided flank pain coming in waves (kidney stone)
- With fever and chills (kidney infection — urgent)
- Blood in urine with the pain
- Pain persists more than a week without explanation
- Known history of kidney disease
📚 Sources
This information is based on guidance from:
Always verify important health decisions with your doctor or a qualified healthcare provider.