Pain under your left ribs can come from several different organs and structures packed into that area, including the stomach, spleen, pancreas, left kidney, and the colon. It can also come from the rib cage itself or the lining of your lungs. The cause ranges from something as common as trapped gas to something that needs immediate attention, like a heart-related issue. Where exactly the pain is, what makes it worse, and what other symptoms you have will point toward the most likely explanation.
What’s Under Your Left Rib Cage
The left upper quadrant of your abdomen houses a surprisingly dense cluster of organs. Your stomach sits here, along with the majority of your pancreas, your spleen, the upper portion of your left kidney, and a sharp bend in your large intestine called the splenic flexure. The lower left ribs also protect the base of your left lung. Pain in this region could originate from any of these structures, or from the ribs, cartilage, and muscles of the chest wall itself.
Trapped Gas and Digestive Causes
The single most common reason for pain under the left ribs is something unglamorous: gas. Your large intestine makes a sharp upward turn near the spleen, and this bend (the splenic flexure) is the highest point in the colon. Gas naturally rises, so it tends to collect right here. When enough gas gets trapped, the colon wall stretches and creates a surprisingly intense pain that can feel like something is seriously wrong. This is sometimes called splenic flexure syndrome, and it typically comes with bloating, a feeling of fullness, and discomfort that shifts or eases after passing gas or having a bowel movement.
Gastritis, an inflammation of the stomach lining, is another frequent culprit. It produces a gnawing or burning ache in the upper belly that may get worse or better after eating. Peptic ulcers cause similar pain. Both tend to create a deep, dull discomfort rather than a sharp, stabbing sensation, and they often come with nausea, loss of appetite, or a feeling of being full too quickly.
Costochondritis and Chest Wall Pain
If the pain gets worse when you press on your ribs, twist your torso, take a deep breath, or cough, the source may be your chest wall rather than an internal organ. Costochondritis is inflammation of the cartilage connecting your ribs to your breastbone. It causes a sharp or aching pain that often affects the left side, can radiate to your arms and shoulders, and worsens with any movement of the chest wall. It can feel alarming because the sensation mimics heart-related pain, but it’s typically harmless and resolves on its own over days to weeks.
Strained intercostal muscles (the small muscles between your ribs) produce a similar pattern. If you recently exercised, lifted something heavy, or had a prolonged coughing episode, a muscle strain is a strong possibility. The key feature with all chest wall causes is that pressing on the area reproduces the pain, something that doesn’t happen with organ-related problems.
Spleen Problems
Your spleen sits just behind and below your left ribs. When it becomes enlarged (a condition called splenomegaly), it can press against surrounding structures and cause a dull ache or sense of fullness under the ribs. You may feel full after eating only a small amount because the swollen spleen pushes against the stomach. Infections like mononucleosis are a common cause of spleen enlargement in younger adults.
Less commonly, blood flow to the spleen can be blocked, causing a splenic infarct. In a study of patients diagnosed with this condition, about 50% reported localized left-sided abdominal pain, and roughly a third had nausea or vomiting. More than a third had a fever. Splenic infarcts typically occur in people who already have a blood disorder, a clotting condition, or have experienced abdominal trauma, so this is unlikely if you’re otherwise healthy and haven’t been injured.
Pancreatitis
The pancreas stretches across your upper abdomen, with most of it sitting on the left side. When it becomes inflamed, the pain centers in the upper belly and often radiates to the back or shoulders. Eating makes it worse, sometimes significantly. Acute pancreatitis usually comes on suddenly and feels severe. You might also have nausea, vomiting, and a rapid heartbeat. Chronic pancreatitis causes a more constant upper-belly pain that flares after meals.
Heavy alcohol use and gallstones are the two most common triggers. If you have steady, worsening pain in the upper abdomen that bores straight through to your back and gets noticeably worse after eating, pancreatitis is worth considering.
Kidney Stones
A stone forming in or passing through the left kidney can produce pain that starts in your lower back or side, right around where the ribs end. The pain often radiates downward toward your groin. It tends to come in waves, building to an intense peak and then easing off before starting again. This colicky pattern, along with blood-tinged urine or a strong urge to urinate, helps distinguish kidney stone pain from other causes. The pain can be severe enough to make it hard to sit still.
Pleurisy
The lining around your lungs has two thin layers that normally glide smoothly over each other as you breathe. When these layers become inflamed, a condition called pleurisy, they rub together like sandpaper. This creates a sharp, stabbing chest pain that gets worse every time you inhale, cough, or sneeze. A distinctive feature: the pain lessens or stops entirely when you hold your breath. It can also spread to your shoulders or back. Pleurisy is often triggered by a viral infection and usually resolves as the underlying illness clears.
How Doctors Figure Out the Cause
When the cause isn’t obvious from your symptoms alone, imaging is the next step. A CT scan with contrast is considered the most reliable tool for evaluating left upper quadrant pain across nearly all scenarios. It provides high-resolution images of the spleen, pancreas, kidneys, and surrounding tissues, and it can detect problems like splenic infarction, abscesses, and pancreatic inflammation with high sensitivity.
Ultrasound is a good initial option for certain situations, particularly when the concern is an enlarged spleen. It’s noninvasive, fast, and effective at measuring spleen size and checking blood flow. However, it’s less reliable than CT for detecting infections and abscesses. Standard abdominal X-rays have a limited role and are generally not recommended as a first-line test for this type of pain.
When Left-Sided Rib Pain Is an Emergency
Most causes of pain under the left ribs are not dangerous, but a few require immediate attention. Heart disease, including heart attacks, can present as pain or pressure in the upper abdomen under the rib cage, sometimes accompanied by severe nausea. This is especially true in women and older adults, where heart attack symptoms are more likely to feel like abdominal discomfort than classic chest pain.
Head to an emergency room if you experience any of the following alongside your left-sided pain:
- Pain so severe it’s hard to move, eat, or drink
- Sudden onset of intense pain
- High fever
- Blood in your stool or vomit
- Pain following an accident or trauma to the abdomen
- Pressure, tightness, or squeezing in the chest, especially with shortness of breath, dizziness, or pain radiating to the jaw or arm
If there’s any doubt about whether the pain could be heart-related, treat it as an emergency. That’s one situation where being cautious is always the right call.