Many conditions can cause back and side or flank pain. According to the University of Maryland Medical Center, pain that arises in the flank or side can signal kidney problems, although numerous other health problems can cause side pain. In some cases, flank pain is accompanied by back pain. Back and flank pain may be caused by the same condition or they may be caused by separate conditions.
Chronic Unilateral Obstructive Uropathy
Chronic unilateral obstructive uropathy, or CUOU, can cause back and flank pain. According to the MedlinePlus website, CUOU is a condition in which there is a longstanding obstruction or blockage of one of the ureters that transports urine from the kidneys to the bladder. The most common cause of CUOU is a kidney stone that blocks the flow of urine through the ureter, causing a back-flow of urine and a swelling of the kidney known as hydronephrosis. Other possible causes of CUOU include congenital malformations of the ureter and abdominal or pelvic surgery that damages the ureter. Common signs and symptoms associated with CUOU include one-sided back and flank pain, abdominal pain, blood in the urine, a persistent urge to urinate, painful urination and a urinary tract infection. CUOU occurs in about five out of every 1,000 people, states the MedlinePlus website.
Polycystic Kidney Disease
Polycystic kidney disease can cause back and side pain. The National Institute of Diabetes and Digestive and Kidney Diseases, or NIDDK, states that polycystic kidney disease is a genetic disorder in which numerous cysts--fluid-filled sacs--form in the kidneys. The kidneys are paired abdominal organs that filter metabolic waste products and fluid from the blood to form urine. According to the NIDDK, polycystic kidney disease causes a significant enlargement of the kidneys, which in turn causes much of the kidney's normal structure to be replaced. Polycystic kidney disease leads to decreased kidney function and even kidney failure. Common signs and symptoms associated with polycystic kidney disease include urinary tract infections, blood in the urine, elevated blood pressure, kidney stones and numerous other co-existing medical conditions.
Herpes Zoster
Herpes zoster, also known as shingles, can cause back and flank pain. According to the American Academy of Dermatology or AAD, anybody who has had chicken pox can develop herpes zoster. In fact, approximately 20 percent of people who have had chicken pox will get shingles. After the chicken pox disappear, the varicella-zoster virus--the virus that causes chicken pox--lies dormant or inactive within certain nerve cells in the body. In times of stress or when a person's immunity weakens, the virus may reactivate, causing a painful rash and fluid-filled blisters that form in a band-like pattern that wraps around one side of a person's torso or other part of the body. Common signs and symptoms of herpes zoster include extreme pain in the affected area before and during an outbreak, skin burning, itching, tingling and hypersensitivity, fever and headache. The AAD states that shingles-related blisters usually last for about two to three weeks.
