Flank Pain (Right and Left Side) – List of Causes

We all experience flank pain every now and then in life but usually it is short-lived and resolves without the need for any medical treatment. As such most of us do not give much consideration for this momentary flank pain, which is also described at times as ‘side pain’. However, like any part of the body pain that is persistent or worsening over time can be a sign of some serious underlying medical problem. Pain should never be ignored especially where it presents with other symptoms as early diagnosis and treatment can at times be a matter of life and death.

What is flank pain?

Flank pain is term used to describe pain that is localized to the sides of the abdomen. Technically the flank includes the chest cavity and extends from the hip to the armpits but most of the time we tend to think of flank pain as isolated to the abdominal area. Pain higher up that extends to the chest area is often termed as chest pain althogh the flank includes the entire torso. Flank pain is a symptom that may occur on its own or be accompanied by other symptoms, depending on the organ that is diseased.

Always consult with a medical professional for flank pain that is worsening and accompanied by symptoms such as dizziness, difficulty breathing, confusion and fainting. A host of serious acute conditions may present with flank pain often along with these other symptoms and immediate medical attention is necessary. For long-standing flank pain, it is important to identify other symptoms and triggers of the pain in order to isolate a possible cause of the pain.

Causes of Flank Pain

Considering the number of organs and structures within the abdomen and chest cavities, flank pain may be due to any number of diseases. Our focus is on flank pain isolated to the abdominal region although problems involving the chest region should also be considered when assessing pain closer towards theĀ  armpits. Flank pain is therefore most likely due to problems with the organs that lie the closest to the side borders of the abdomen. However, possible causes of chest pain such as lung infections, lung cancer, angina pectoris, heart attacks, pericarditis and pleuritis should not be ruled out without conducting further tests for upper flank pain.

Abdominal Wall

The abdominal wall comprises the skin, superficial fat tissue, connective tissue and muscles on the surface of the abdomen. Injury or diseases affecting any of these structures can give rise to flank pain. One of the more common causes of flank pain due to a problem with the abdominal wall is muscle strain. This is often experienced with strenuous physical activity like abdominal exercises or after running a long distance. A blow to the area is another common abdominal wall cause of flank pain. A fractured rib can also cause flank pain although this is typically felt within the chest area.

Kidneys and Urinary System

Another common cause of flank pain is due to the urinary organs. The kidney lie high up in the abdomen, largely shielded behind the ribcage. Therefore problems with the kidneys such as pyelonephritis (infections) and kidney stones are more often felt on the flank under the ribcage or at the mid back region. The ureters then carry urine from the kidneys to the bladder in the pelvis. Diseases of the ureters such as stones within it (usually kidney stones), infections and strictures (narrowings) can also cause flank pain.


The bulk of the liver lies on the right side of the abdomen in the upper quadrants. Therefore right sided flank pain that lies higher up in the abdomen may be due to liver diseases. This can includes conditions such as hepatitis, hepatocellular carcinoma (liver cancer), bile duct obstruction and may also occur with gallbladder diseases that affects the liver function. The pain is usually also felt on abdominal surface and there may be accompanying symptoms such as jaundice, nausea and fever.


The majority of the large intestine runs along the flanks both on the right and left side. On the right flank lies the cecum and ascending colon whereas on the left flank runs the descending colon. Diseases affecting the colon may therefore also present with flank pain. This may include conditions such as infections (gastroenteritis or enterocolitis), inflammatory bowel disease, diverticulitis and colorectal cancer at the extreme end of the spectrum. Usually there are changes in bowel habit such as diarrhea or constipation along with abdominal cramping and nausea.


Gynecological causes of flank pain in women are an important consideration due to the ovaries lying more towards the sides. While this can be largely termed as ovarian pain, conditions affecting the fallopian tubes also needs to be considered. Possible gynecological causes vary from polycystic ovarian syndrome (PCOS) to ectopic pregnancy, endometriosis and ovarian cancer. Apart from the pain there are other symptoms like abnormalities in menstruation, difficulty falling pregnant, severe menstrual pain and associated changes in the female hormone levels.


On the upper part of the left flank lies the spleen. It serves as a reservoir for blood and plays an important role inimmune functions within the body. The spleen is well protected by the ribs but any injury to the spleen, inflammation or even spleen rupture can cause upper left-sided flank pain. This is more often seen with injuries sustained during a fall, assault or motor vehicle accident. Enlargement of the spleen, known as splenomegaly, is rarely painful.


The stomach mainly sits in the upper left side of the abdomen. It is located next to the spleen and while diseases of the stomach tend to present with left upper quadrant abdominal pain, it may sometimes also left flank pain. Conditions such as gastritis, stomach ulcers, gastroenteritis and a Mallory-Weiss tear where the esophagus meets the stomach are some of the possible causes along with a host of other stomach diseases. Apart from the pain there may be nausea, vomiting, changes in appetite and bloating.

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