Side back pain is also known as flank pain. Side pain is very common and may arise from the muscles, ligaments, tendons or from any of the abdominal organs. In most cases only one side of back pain is the problem- either the left or right. In the majority of cases, side pain is due to dysfunction of the abdominal organs. The side pain may vary in intensity and can be very uncomfortable. If the side pain is due to an internal abdominal organ it may also be associated with fever, chills, difficulty breathing, blood in the urine or abdominal cramps. Side pain can also be from muscle spasms that are common in people who exercise, lift weights or work in one position.

In the elderly, side or flank pain may be from shingles. Shingles is caused by the chicken pox virus and can present with a red linear rash that is followed by painful vesicles. Shingles lasts for 14-21 days and can be excruciating.

One of the most common causes of lower side back pain is kidney stones. Pain from kidney stones usually starts in the flanks and then radiates to the pubic area. The pain comes in waves and can be very intense and is often associated with sweating, dizziness and chills. Some people may notice blood in the urine. The diagnosis of kidney stone is made by a radiological dye study or a CT scan. Most small stones do pass but this can be very painful. Hospitalization is very rare for individuals who have a kidney stone unless it is associated with an infection. When the kidney stones fail to pass into the urine, some type of procedure may be required to remove the stone. Sometimes ultrasound is used to break up the stones into pieces and then the stone fragments pass into the urine. Rarely some type of surgery may be required to retrieve a large stone stuck in the ureter or bladder.

There are some people who develop an infection of the kidney known as pyelonephritis. This is an acute infection which usually starts on the side and is very painful. Almost all individuals have a fever, chills and may have difficulty passing urine. The treatment of pyelonephritis is pain control, hydration, and antibiotics.

The diagnosis of lower side back pain can be difficult as there are many causes. Depending on the symptoms and clinical history, one may undergo an ultrasound, MRI, urine analysis, blood culture or a CT scan. In some cases, even constipation can present with back pain on rigth side and confuse the physician. Females who have missed their menstrual cycle may have an ectopic pregnancy which can also present with side pain.

It is difficult to know if flank pain is serious. Therefore it is essential to contact a health care professional if the flank pain is associated with 1) fever, 2) chills, 3) vomiting, blood in the urine or pain which is intense and unrelenting.

The treatment of side back pain may include antibiotics, muscle relaxants, pain pills, hydration and rest.