Flank pain is localized on one side, beneath the ribs but above the pelvis, and in some cases in the small of the back.  It is important to mention that flank pain is not a condition, but a symptom. Therefore, it can signal various issues, depending on the trigger.

Flank pain usually goes away very quickly, but if the pain doesn’t subdue, it can indicate a serious infection or dehydration. It is very important to learn more about the different triggers in order to understand whether the pain is manageable or seeks further medical attention.


1. Obstructive Uropathy

Obstructive uropathy is basically a blockage which prevents urine from leaving the kidneys. This blockage occurs in the ureter but both ureter and kidneys can experience it. A kidney or bladder stone are the most common causes of an obstruction, but there are other causes as well. Some of them include enlarged prostate, scar tissue, injuries, or cancer. Besides flank pain in the lower back on the side of the affected kidney, a frequent urination is yet another symptom of this issue. The frequency gradually goes up and changes in color and smelling are also very common. Fever, vomiting, raised blood pressure, and nausea can also be present, depending on the cause and duration.

2. Bladder Infection or Urinary Tract Infection (UTI)

Urinary tract infection is an umbrella term for infection caused by yeast, infections or viruses. It doesn’t necessarily cause flank pain, but pressure and cramping in the lower abdomen or back are very common.

Symptoms of UTI include burning sensation when urinating, cloudy or bloody urine, foul-smelling urine, and frequent sense of having to urinate. Women are more prone to UTI than men, as their tracts are shorter and easier to traverse.

3. Pyelonephritis

This is a specific form of kidney infection which can cause permanent damage if left untreated. The flank pain in pyelonephritis is accompanied with a high fever, urine containing blood, a frequent urination, burning sensation when urinating, and foul-smelling urine. Chills, vomiting, moist skin, shaking, fatigue, and mental confusion can also occur, but they are not as consistent.

4. Kidney Stones or Bladder Stones

Kidney and bladder stones are the most common causes of flank pain. The pain is described as one of the most painful experiences you can have and it is sudden and radiation from the pelvis to the groin. The stones are result of calcium deposits which cannot be excreted through urination. Increased urination frequency, blood in the urine, nausea, and vomiting are very common symptoms when it comes to this issue.

5. Cancer

Flank pain can be often a cause by renal cancer, bladder cancer, or certain forms of lymphoma.  The growth results in an abdominal lump, bloody urine, uncontrollable urination, fatigue, and sudden weight loss. Vision problems are not uncommon as well.

6. Appendicitis

The appendix is located in the lower-right area of the abdomen and it is often a place where bacteria and feces collect. As a result, the appendix swells and puts pressure on the nearby vessels. In case it ruptures, all the waste spills into the abdomen.

In case it leaks, it gets infected and it causes abscesses to form. Appendicitis causes pain, loss of appetite, low fever, vomiting, abdominal bloating, constipation, or diarrhea.


As seen, there are various causes for flank pain and they are diagnosed with the help of a combination of techniques.

Renal scan can check kidney function; urinalysis is used to check for blood or infection in the urine, and other techniques include bladder test, abdominal CT or ultrasound.


Given the fact that there are various causes of flank pain, resolving the pain requires a different approach. For instance, in cases of blockage, short-term relief can be given by surgery to reduce scarring, medication to reduce prostate swelling, antibiotics to treat the infection, or stent to keep the ureter open.

Urinary tract infections and pyelonephritis are treated with antibiotics and kidney stones are treated either by passing the stones with medications or surgery. Finally, when it comes to appendicitis, the usual treatment requires surgery to remove the swollen organ and draining of any abscesses.

Source: http://theheartysoul.com/what-side-pain-means/