Your rib cage consists of 24 ribs — 12 on the right and 12 on the left side of your body. Their function is to protect the organs that lie beneath them. On the left side, this includes your heart, left lung, pancreas, spleen, stomach, and left kidney. When any of these organs are infected, inflamed, or injured, pain can radiate under and around the left rib cage. While your heart is under your left rib cage, feeling pain in that area usually doesn’t indicate a heart attack.

Depending on the cause, it might feel sharp and stabbing, or dull and aching. In most cases, left rib cage pain is due to a benign, treatable condition.

Costochondritis

Costochondritis refers to inflammation of the cartilage that attaches your ribs to your breastbone. This can happen for several reasons, such as:

It causes a sharp, stabbing pain that’s usually felt on the left side of your rib cage. It gets worse when you cough, sneeze, or press on your ribs.

Pancreatitis

The pancreas is a gland located near your small intestine in the upper left part of your body. It secretes enzymes and digestive juices into the small intestine to help break down food. Pancreatitis refers to inflammation of your pancreas. This can be due to:

Pain caused by pancreatitis usually comes on slowly and intensifies after eating. It may come and go or be constant. Additional symptoms of pancreatitis include:

  • nausea
  • vomiting
  • weight loss

Ruptured spleen and splenic infarct

Your spleen also sits in the upper portion of the left side of your body, near your rib cage. It helps to remove old or damaged blood cells and produce white ones that fight infection.

An enlarged spleen, also called splenomegaly, usually doesn’t cause any symptoms other than fullness after eating only a small amount of food. However, if your spleen ruptures, you’ll likely experience pain near your left rib cage. An enlarged spleen is more likely to rupture than a normal-sized spleen.

Several things can cause an enlarged spleen, including:

  • viral infections, such as mononucleosis
  • bacterial infections, such as syphilis
  • parasitic infections, such as malaria
  • blood diseases
  • liver diseases

If your spleen ruptures, the area might also feel tender when you touch it. You’ll also likely experience:

  • low blood pressure
  • dizziness
  • blurry vision
  • nausea

A spleen rupture most commonly occurs as a result of trauma. It’s a medical emergency and you should seek medical attention immediately.

You can also experience pain under the left side of your rib cage with a splenic infarction. Splenic infarcts are rare conditions where a portion of the spleen necrotizes or “dies.” This happens when the blood supply is compromised, usually as a result of trauma or arterial blockages.

Gastritis

Gastritis refers to inflammation of the lining of your stomach, which is also near the left side of your rib cage. Other symptoms of gastritis include a burning pain in your stomach and an uncomfortable sense of fullness in your upper abdomen.

Gastritis can be caused by:

Kidney stones or infection

Your kidneys are part of your urinary tract. They’re located on either side of your spine, but when they become inflamed or infected, the pain can radiate to the front. When your left kidney is involved, you might feel pain near the left side of your rib cage.

Kidney stones are hardened calcium and salt deposits that form into stones. They can cause a cramping pain as they move out of your kidneys and make their way toward your bladder. In addition to pain in your left rib cage, kidney stones can also cause:

  • an urge to urinate, with little coming out
  • bloody or cloudy urine
  • pain in your side that radiates to the front of your body

Kidney infections occur when bacteria from your urinary tract make their way into your kidneys. Anything that obstructs your flow of urine, including kidney stones, can cause a kidney infection. Additional symptoms of a kidney infection include:

  • fever
  • nausea
  • vomiting

Pericarditis

Your heart is surrounded by a fluid-filled sac called the pericardium. Pericarditis refers to inflammation of this sac. When it’s inflamed, it can rub against your heart causing pain near your left ribs. The pain may be a dull ache or a stabbing pain that’s usually worse when lying down.

Researchers aren’t sure why it happens, but possible causes include:

  • infection
  • injury
  • certain blood thinners
  • anti-seizure medications

Pleurisy

Pleurisy is a condition in which the tissue that covers the lungs becomes inflamed. This can occur as a result of bacterial, viral, or fungal pneumonia, malignancy, trauma, or pulmonary infarction usually related to a blood clot in the lung.

Pleurisy on the left side may cause pain under the left rib cage, but the main symptom is a sharp, stabbing pain when you breathe. See a doctor if you experience any intense chest pain during breathing.

To figure out what’s causing pain in your left rib cage, your doctor will give you a physical exam that includes feeling the affected area. This will help them check for any signs of swelling or inflammation, especially due to costochondritis.

If they suspect the pain could be due to a heart problem, your doctor might use an electrocardiogram to measure the electrical activity in your heart. This will help to rule out any serious underlying condition.

Next, they may take blood and urine samples for testing. Analyzing these results can alert your doctor to signs of kidney problems, pancreatitis, or gastritis. If you doctor suspects you might have gastritis, they may also take a stool sample or use an endoscope to look at your stomach lining. An endoscope is a long, flexible tube with a camera on the end that’s inserted through your mouth.

If the cause of your rib cage pain still isn’t clear, you may need an X-ray, CT scan, or MRI. This will give your doctor a better view of your organs and any areas of inflammation that didn’t show up during the physical exam.

Treating your left rib cage pain depends on what’s causing it. If it’s related to any type of inflammation, your doctor will likely recommend you take NSAIDs to reduce pain and swelling.

In some cases, you may need an antibiotic to clear up a bacterial infection. In rare cases, you may need surgery. For example, if a kidney stone is too large to pass through your body on its own, your doctor may need to surgically remove it.

While pain in your left rib cage is usually nothing serious, it can sometimes signal a medical emergency.

Seek emergency treatment if you have any of the following in addition to pain in your left rib cage:

  • trouble breathing
  • mental confusion
  • excessive sweating
  • lightheadedness or dizziness

Given the number of organs in the upper left part of your body, it’s not uncommon to feel pain under the left rib cage. It may be caused be an easily treatable condition.

However, if you have pain in this area that’s severe, worsens over time, lasts more than 24 hours, or is associated with any of the serious symptoms above, you should seek medical treatment immediately to rule out any underlying conditions.