Pain under the left rib cage can come from several different organs and structures packed into that area, including the spleen, stomach, pancreas, left kidney, colon, and the lower portion of the left lung. The cause ranges from something as routine as trapped gas to something as urgent as a heart attack, so the specific quality of the pain and any accompanying symptoms matter a lot in narrowing it down.
Trapped Gas and Splenic Flexure Syndrome
One of the most common and least dangerous causes is gas buildup in the part of the colon that makes a sharp bend near the spleen, called the splenic flexure. Gas traveling through the large intestine normally negotiates this curve without trouble, but when there’s too much of it, the bend acts like a bottleneck. Cleveland Clinic compares it to heavy rain rushing toward a sharp bend in a river. The result is bloating, cramping, and a sometimes surprisingly intense pain just under the left ribs. Some people are born with a tighter bend in this section of the colon, making them more prone to the problem.
This kind of pain tends to come and go, often worsens after meals, and usually improves after passing gas or having a bowel movement. It can feel alarming because of where it’s located, but it’s not dangerous on its own.
Gastritis
Your stomach sits close to the left side of the rib cage, so inflammation of its lining (gastritis) frequently shows up as pain in that area. Gastritis doesn’t always cause noticeable symptoms, but when it does, you may feel a gnawing or burning ache in the upper abdomen, nausea, vomiting, or a sense of fullness after eating only a small amount. Common triggers include overuse of anti-inflammatory painkillers, heavy alcohol consumption, and infection with the bacteria H. pylori.
Enlarged Spleen
The spleen sits directly behind the left rib cage, and when it swells (a condition called splenomegaly), it can press against surrounding structures and cause pain or a feeling of fullness in the left upper abdomen. That discomfort sometimes radiates to the left shoulder. Because the enlarged spleen pushes against the stomach, you may also feel full after eating very little.
An enlarged spleen is not a disease in itself but a sign of something else going on. The list of possible underlying causes is long: viral infections like mononucleosis, liver disease including cirrhosis, blood cancers like leukemia or lymphoma, autoimmune conditions like lupus, hemolytic anemias that destroy red blood cells prematurely, and even blood clots in the veins around the spleen or liver. Many people with a mildly enlarged spleen have no pain at all and only discover the problem during an imaging scan for another reason.
Pancreatitis
The pancreas sits behind the stomach on the left side of the abdomen. When it becomes inflamed, the pain can be sudden and severe (acute pancreatitis) or develop gradually over months and years (chronic pancreatitis). The pain typically starts in the upper abdomen and often wraps around to the back, which helps distinguish it from many other causes on this list. Other signs include fever, a rapid heart rate, nausea, vomiting, and in chronic cases, unexplained weight loss or yellowing of the skin.
Gallstones and heavy alcohol use are the two most frequent triggers for acute pancreatitis. Chronic pancreatitis can result from repeated bouts of acute inflammation or from long-term alcohol use.
Costochondritis and Rib Injuries
Not all pain under the left rib cage comes from an organ. The cartilage connecting the ribs to the breastbone can become inflamed, a condition called costochondritis. It often develops gradually after repeated minor trauma or unaccustomed physical activity like painting a ceiling or moving furniture. The pain gets worse with trunk movement, deep breaths, or exertion, and it eases when you stay still and breathe quietly. In more than 90% of cases, multiple rib junctions are tender to the touch, and some people don’t even realize the area is sore until a doctor presses on it.
A related but distinct condition called Tietze syndrome also causes rib cartilage tenderness, but it comes on acutely and produces visible swelling, warmth, and redness over the affected joints, typically the second or third ribs. Costochondritis, by contrast, has no visible swelling. Direct rib fractures or bruised ribs from a fall, car accident, or contact sport also cause sharp, localized pain that worsens with breathing and movement.
Pleurisy
The lower left lung extends down behind the rib cage, and inflammation of the thin membrane surrounding it (called the pleura) produces a distinctive stabbing pain that sharpens every time you inhale, cough, or sneeze. A useful clue: the pain lessens or stops entirely when you hold your breath. It can also worsen when you move your upper body and may spread to the shoulder or back. Pleurisy is usually triggered by a viral or bacterial infection, though it can also result from a blood clot in the lung or an autoimmune condition. If enough fluid accumulates between the pleural layers, the pain may actually diminish because the inflamed surfaces are no longer rubbing against each other.
Kidney Stones and Infections
The left kidney sits toward the back of the abdomen, partially tucked behind the lower ribs. Kidney stones typically cause pain in the lower back, side, or belly that can radiate down toward the groin. The pain is sometimes dull but often sharp and severe, and it tends to come in waves rather than remaining constant. Because the kidney sits high enough to overlap with the rib area, some people perceive stone pain as originating under the left ribs, especially when the stone is still in the upper portion of the urinary tract. A kidney infection can produce similar flank pain along with fever, chills, and painful urination.
When It Could Be Your Heart
Pain or pressure under the left rib cage can occasionally signal a heart attack, even when it doesn’t match the classic “crushing chest pain” image. People experiencing a cardiac event more often describe the sensation as squeezing, tightness, or pressure rather than sharp pain. It may feel like something heavy is sitting on the chest, and the discomfort can spread to the jaw, back, neck, or arms. If left rib pain comes with shortness of breath, lightheadedness, cold sweats, or nausea, and especially if it’s a new sensation you’ve never felt before, calling emergency services is the right move. An electrocardiogram can usually confirm or rule out a heart attack within minutes.
How Doctors Figure Out the Cause
When left upper abdominal pain is acute, a CT scan with contrast is the most reliable first-line imaging test. It provides a wide field of view with high resolution and can identify problems ranging from a splenic infarction to an abscess to pancreatitis. If the main concern is an enlarged spleen specifically, an abdominal ultrasound is also considered appropriate and has the advantage of being noninvasive and radiation-free. Ultrasound is less useful when the pain is nonspecific, because its sensitivity drops compared to CT for detecting many abdominal conditions. Standard abdominal X-rays are generally not recommended for evaluating this type of pain, as they miss most of the relevant diagnoses and often just delay getting the right scan.
Beyond imaging, blood tests can check for signs of infection, inflammation, liver or pancreatic enzyme abnormalities, and heart muscle damage. The specific combination of tests depends on which symptoms accompany the pain, whether there was an injury, and how suddenly the pain started.