Side pain (also called flank pain) is discomfort that occurs on the left or right side of the torso between the armpits (axilla) and the hips. These general areas contain bones, muscles, nerves, blood vessels, organs, and other structures that can become infected, inflamed or damaged.

Side pain can also radiate to or from the front or back of the torso, especially the abdomen, chest, and middle to lower back area. The chest cavity contains the lungs, heart and other major structures of the respiratory and cardiovascular system, in addition to organs and structures of the digestive, nervous and lymphatic systems. The abdominal cavity contains the stomach, intestines, liver, gallbladder, kidneys, spleen and pancreas. Side pain can be a symptom of a wide variety of mild to serious diseases, disorders and conditions, such as infection, infarction, inflammation, indigestion, trauma, intestinal obstruction, and cancer. Side pain can occur on one or both sides of the torso at a time. Side pain can be described as mild and dull or a severe cramp-like feeling. Depending on the cause, side pain can occur suddenly and disappear relatively quickly, such as when you experience a stitch in your side from running or other vigorous exercise. It can also build for a period of months and years if it is due to a slow-growing tumor or organ disease.

Seek prompt medical care if you have unexplained or persistent side pain or if you are concerned about your symptoms. Prompt diagnosis and treatment of side pain can help control symptoms and reduce the risk of complications of underlying diseases, disorders and conditions.

Seek immediate medical care (call 911) if you have side, back or abdominal pain after trauma or injury, shortness of breath, blood in your vomit or stools, dizziness or fainting, sudden abdominal swelling, or chest pain, which may radiate to your shoulder blades, jaw, or left arm.

Symptoms
What other symptoms might occur with side pain?
Side pain may accompany other symptoms, which vary depending on the underlying disease, disorder or condition.

Digestive symptoms that may occur with side pain
Side pain may accompany symptoms affecting the digestive tract including:

Belching

Diarrhea

Flatulence and gas

Indigestion

Nausea

Poor appetite

Vomiting

Other symptoms that may occur with side pain
Side pain may accompany other symptoms related to body systems other than the digestive tract. Symptoms may include:

Abdominal pain

Flu-like symptoms (fatigue, fever, chills, sore throat, headache, cough, aches and pains)

Increased side or abdominal pain with breathing or movement

Low back pain that may radiate or move to the groin and testicles or labia

Urination symptoms, such as frequent urination or burning with urination

Yellow skin and eyes (jaundice)

Serious symptoms that might indicate a life-threatening condition
In some cases, side pain may accompany symptoms that might indicate a serious or life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) for side pain accompanied by any of the following symptoms:

Bloody or black stools

Chest pain or pressure which may or may not radiate to your shoulder blades, jaw, or left arm

Difficulty breathing or shortness of breath

Dizziness that is severe or sudden and unexplained

Fainting, lethargy, confusion, disorientation or other change in level of consciousness or alertness

Not producing any urine

Pulsating mass in abdomen

Rib cage deformity

Severe abdominal, side, flank or back pain

Vomiting blood or black material (resembling coffee grounds)

Causes
What causes side pain?
Side pain can be caused by a wide variety of mild to serious diseases, disorders and conditions. Relatively mild conditions that can cause side pain include indigestion and exercising too much. Serious and life-threatening conditions that can cause side pain include heart attack and trauma.

Urinary causes of side pain
A common source of side or flank pain is kidney disease and other conditions of the kidney including:

Kidney abscess

Kidney cancer

Kidney infarction (death of kidney tissue due to lack of oxygen)

Kidney infection (pyelonephritis)

Kidney stones

Kidney trauma

Ureteral obstruction (acute or chronic) due to such conditions as a congenital anomaly, blood clot, or kidney stone

Gastrointestinal causes of side pain
Side pain may occur by itself or in conjunction with abdominal pain due to diseases and conditions of the digestive tract including:

Appendicitis

Bowel blockage or obstruction

Colorectal or pancreatic cancer

Diverticulitis

Flatulence (gas)

Food poisoning and viral gastroenteritis

Gallbladder disorders including gallstones, biliary colic, or cholecystitis

Inflammatory bowel disease (includes Crohn’s disease and ulcerative colitis)

Irritable bowel syndrome and food intolerances or allergies to certain foods

Liver disorders (liver abscess, hepatitis, cirrhosis, liver failure, or liver cancer)

Pancreatitis

Ruptured spleen

Lung-related causes of side pain
Side pain can be caused by serious problems with the respiratory system. Although the following conditions may be most commonly associated with pain centered in the chest, the pain can radiate to the side of the chest, ribcage or back in some cases. Respiratory conditions include:

Asthma

Bronchitis

Chronic obstructive pulmonary disease (COPD; includes emphysema and chronic bronchitis)

Pleurisy (inflammation of the lung lining)

Pneumonia

Pneumothorax or hemothorax (collapsed lung or blood around the lung)

Pulmonary edema (buildup of fluid in the lungs)

Pulmonary embolism (blood clot that travels to the lung)

Pulmonary hypertension (high blood pressure in the arteries of the lungs)

Tuberculosis (serious infection affecting the lungs and other organs)

Gynecological causes of side pain
Female reproductive organs may become inflamed, infected, or otherwise damaged, causing pain on one or both sides of the lower abdomen above the groin. Gynecological causes of side pain include:

Ectopic pregnancy

Ovarian cysts or rupture of ovarian cysts

Ovulation

Salpingitis (inflammation of the fallopian tubes)

Tubo-ovarian abscess (abscess affecting an ovary and fallopian tube)

Cardiovascular causes of side pain
Side pain, possibly in conjunction with abdominal or chest pain, can arise from serious or life-threatening problems with the heart and the vascular system. Although the following conditions are often associated with frontal chest pain, the pain can radiate to the side of the chest, ribcage or back in some cases. Cardiovascular conditions include:

Abdominal aortic aneurysm

Aortic dissection

Congenital cardiac anomalies, disorders, and birth defects, such as coarctation of the aorta and aortic valve stenosis

Congestive heart failure

Coronary artery disease (heart disease) including coronary artery spasm or angina due to atherosclerosis (hardening and narrowing of the arteries)

Endocarditis (inflammation or infection of the inner lining of the heart)

Heart attack

Mitral valve prolapse and other heart valve problems

Pericarditis (inflammation or infection of the lining that covers the heart)

Thoracic aortic aneurysm

Other causes of side pain
Other causes of side pain include:

Exercise

Fibromyalgia (chronic condition that causes pain, stiffness and tenderness)

Hernia

Muscle spasm

Musculoskeletal injuries, such as a rib fracture or strained muscle in the chest wall, back, or abdomen

Neuritis (inflammation of a nerve between ribs)

Rib infection

Seminal vesiculitis (seminal vesicle inflammation)

Shingles (herpes zoster infection)

Questions for diagnosing the cause of side pain
To diagnose the underlying cause of side pain, your doctor or licensed health care provider will ask you questions about your symptoms. You can best help your health care provider diagnose the underlying cause of side pain by providing complete answers to these questions:

When did the pain start?

Do you feel pain on one side or both sides?

Does the pain go from your side to another part of your body such as your groin, abdomen or chest?

Have you been injured recently?

How would you describe the pain? Examples include cramp-like, dull, sharp, constant, and intermittent.

What medications have you recently taken?

What other symptoms do you have?

What are the potential complications of side pain?
Complications of the underlying causes of side pain vary. Any kind of unexplained or persistent side pain, whether it occurs alone or is accompanied by other symptoms, should be evaluated by your doctor or health care provider. Once the underlying cause is identified, following the treatment plan you and your health care provider develop specifically for you will minimize the risk of complications of serious or life-threatening underlying causes of side pain including:

Cardiac arrest

High carbon dioxide levels and acidosis

Injury to organs and structures in your chest and abdomen including your arteries, kidneys, lungs, liver and spleen

Respiratory failure and respiratory arrest

Sepsis

Shock

Spread of cancer

Spread of infection