Side Pain (Right and Left) Causes and Other Symptoms

Pain in the torso can be described in many ways. Usually it is described by the specific area, for example chest pain to refer to the upper torso and abdominal pain for the lower section. This correlates to the chest (thoracic) and abdominal cavities respectively. Pain at the rear of the torso is encompassed under the term back pain. The sides of the lower torso are referred to as the flanks. Therefore pain in this area is more correctly known as flank pain although it is often referred to as side pain.

Causes of Side Abdominal Pain

There are various possible causes of side pain. Sometimes it may be related to the same causes as abdominal pain or chest pain. Certain conditions present specifically with lateral (side) pain. The more common of these conditions is discussed below in detail.

Read more on side abdominal pain (flank pain).

Chest Wall

Chest wall problems should always be considered as injuries and strain can arise quite easily. This may occur with a trauma like a blow to the chest, muscle strain, a bruised or broken rib, infections like shingles and various skin diseases. There are many other possible causes of chest wall pain that also need to be considered. Usually chest wall pain presents with additional symptoms like a hematoma, rash or visible deformity.


Side pain on the upper part of the torso is often associated with lung conditions. The lungs occupy most of the thoracic cavity and sit next to the side chest wall, separated only by a thin membrane (pleura) and space. The pain may also be felt under the arms (armpits/axillae).

  • Pleuritis is where the lining around the lung (pleura) becomes inflamed, often due to an infection. It may at times be part of a lung infection (pneumonia).
  • Pneumonia is an infection of the lung. It may be due to bacteria, viruses and is sometimes caused by fungi. It should not be confused with other other lung conditions such as pneumoconiosis and pneumonitis.
  • Pulmonary embolism is more of a vascular condition that a lung condition. It arises when a blood clot blocks the blood vessels to the lungs thereby impeding blood flow and oxygen distribution.

There are various other possible lung conditions that may also be the cause of chest pain. Few presents with side pain distinctly. Usually there are respiratory symptoms that are also present, like a coughing and difficulty breathing.


Most of the time we think of kidney problems when we experience side pain. This is understandable since the kidneys are located at the flanks, tucked under the lower rib cage within the abdominal cavity. Contrary to popular belief, the kidneys are not located low down by the pelvic (hip) bone.

  • Kidney stones are one of the more common conditions that causes side pain. It occurs when large stones form in the kidneys, usually as a result of sedimentation of the substances within urine. Small stones may pass out of the kidney and then cause pain as it passes down the ureter to the bladder.
  • Kidney infection (pyelonephritis) is another fairly common condition that is usually due to bacteria. These bacterial infections may arise as an bladder infection that ascends up the ureter to the kidney. It is also possible that the bacteria may reach the kidney through the bloodstream from other sites.
  • Kidney trauma arises with blunt or sharp force trauma to the front, back or side of the torso. With blunt force trauma this is usually referred to as a kidney punch or kidney blow. The extent of the trauma depends on the severity of the injury and in some cases can be life-threatening when there is excessive bleeding.
  • Kidney abscess is where pus collects within the kidney tissue. This is usually associated with an infections. Sometimes multiple abscesses can form. It can be very serious especially if the abscess ruptures as the bacteria within it can easily spread to neighboring tissue and even throughout the body.
  • Kidney cancer is where a malignant growth develops in the kidney. It may arise in the kidney in the instance of primary cancer (like renal cell carcinoma) or it may arise elsewhere in the body and then spread to the kidney (secondary or metastatic spread).


The organs of the digestive system occupy most of the space within the abdominal cavity. Digestive causes should always be investigated when there is lower side pain, especially when there are digestive symptoms like nausea, vomiting, alterations in bowel movement (constipation or diarrhea) and changes in appetite.

  • Inflammatory bowel disease (IBD) is a condition where the bowels are inflamed due to autoimmune factors. The colon is a common site and side pain may be present when the ascending and descending colon is affected specifically.
  • Irritable bowel syndrome (IBS) is a functional bowel disorder where there is abnormalities in bowel motility. Abdominal cramps is a common symptom as the muscles in the bowel wall go into spasm which is thought to be the cause of IBS pain.
  • Appendicitis is inflammation of the vermiform appendix which is a small narrow outpouching from the cecum of the large intestine. If it ruptures it can be life-threatening.
  • Diverticulitis is a condition where the abnormal pouches that form in the colon (known as diverticula) becomes inflamed. This is more often seen in the elderly.
  • Colorectal cancer is where a malignant growth forms in the colon and/or rectum. It has become one of the more common cancers in the developed world.
  • Liver diseases such as hepatitis, liver cancer and a liver abscess may also cause side pain, particularly upper right flank pain.
  • Other digestive and gastrointestinal conditions:
    – Pancreatitis and pancreatic cancer
    – Food intolerance and allergies
    – Gallbladder diseases
    – Gastroenteritis and food poisoning
    – Bowel obstruction


Gynecologic conditions needs to be considered when girls or women experience lower side pain. A host of conditions may be the cause, including ectopic pregnancy, polycystic ovarian syndrome (PCOS), pelvic inflammatory disease, ovulation. There may be accompanying gynecologic symptoms like changes in menstrual bleeding, alterations in the menstrual cycle and even difficulty falling pregnant.

Other Causes

  • Ruptured spleen
  • Heart attack
  • Abdominal hernia
  • Strenuous exercise
  • Fibromyalgia

Causes of Side Chest Pain

Chest pain away from the center (breastbone) is primarily due to diseases of the lung and associated structures like the pleura, or of the chest wall itself (skin, ribs, cartilage, muscles but not the breastbone). However, pain that originates centrally, as discussed under pain in the center of the chest, may also refer more laterally (towards the sides of the chest).

Injury/Trauma and Strain

  • Fractures
    • Rib fractures need to be excluded as a cause of non-central chest pain especially if the onset was preceded by trauma. This may include a blow, blunt force trauma, car accident, fall or even a firm grasp around the chest (squeeze, ‘bear hug’).
  • Collapsed Lung
    • A pneumothorax (collapsed lung) may also occur with a rib fracture and sharp force injury that penetrates the chest wall.
  • Muscle Strain
    • The intercostal and pectoral muscles may also chest pain. Weight lifting, strenuous physical activity especially if it involves the upper limbs, a persistent cough and strained breathing may result in muscle strain or tears.
  • Cartilage Inflammation
    • Tietze’s syndrome (costochondritis) affects the costal cartilages and or the joints with the rib or sternum (breastbone). This may arise from strain or injury but is also seen in inflammatory diseases like rheumatoid arthritis.
  • Nerve Compression
    • Pressure or injury of the intercostal nerve at its root (pinched nerve) or along its course will result in pain.


  • Lungs
    • Pneumonia is the inflammation of the lung tissue usually as a result of infection.
    • Pulmonary tuberculosis is a lung infection caused by the bacteria, Mycobacterium tuberculosis.
  • Airways
    • Bronchiectasis is when the airways (bronchi, bronchioles) widen and become scarred due to prolonged inflammation from an infection.
  • Pleurisy
    • Inflammation of the pleura (pleuritis) may be due to many factors including an infection and may arise with pneumonia or tuberculosis.
  • Chest Wall
    • Shingles caused by the herpes zoster virus may result in pain as a result of nerve injury.
    • Bornholm’s disease is a condition that results in muscle pain (myalgia) caused by the Coxsackie group B virus.


This may cause pain within the thoracic cavity or affect the chest wall.

  • Lung cancer
  • Mesothelioma
  • Metastasis from a neighboring or distal site
  • Bony metastases – rib


  • Pulmonary infarction is the death of lung tissue due to a lack of oxygen often as a result of a pulmonary embolus.
  • Connective tissue diseases like SLE (systemic lupus erythematosus).
  • Referred pain from conditions affecting the bronchi, heart, mediastinum, esophagus, stomach, colon, liver.

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