Pain on the left side under the ribs can stem from structures in the chest wall, the upper abdomen, or even organs you might not immediately suspect, like the lungs or kidneys. The left upper quadrant of the abdomen houses the spleen, the tail of the pancreas, part of the stomach, part of the colon, and the left kidney sits just behind the ribs. On top of all that, the ribs themselves, along with the muscles, cartilage, and nerves running between them, are frequent pain generators. Because so many different tissues overlap in this area, the cause can range from a pulled muscle to a medical emergency, and what the pain feels like, how it started, and what makes it worse are often more useful clues than the location alone.
Musculoskeletal Problems Are the Most Common Culprit
If the pain gets worse when you press on the area, twist your torso, or take a deep breath, the likeliest explanation is something in the chest wall itself rather than an internal organ. Costochondritis, which is inflammation where the ribs attach to the breastbone or where cartilage meets bone, is one of the most frequent causes of chest-wall pain and can easily be felt along the left rib margin.1PubMed Central. Musculoskeletal chest wall pain It tends to come on gradually, sometimes after a respiratory infection or repetitive upper-body movement, and it can linger for weeks. The pain is usually sharp and localized, and many people initially worry it is heart-related because of where they feel it.
A less well-known but underdiagnosed condition is slipping rib syndrome. The lowest three ribs (ribs eight through ten) are called “false ribs” because they connect to the rib above through cartilage rather than directly to the breastbone. When that cartilage becomes hypermobile, one rib can slide under the rib above it, pinching the intercostal nerve that runs along the underside of the adjacent rib.2PubMed. Slipping Rib Syndrome: A review of evaluation, diagnosis and treatment The result is a clicking or popping sensation along the lower rib cage and sharp, sometimes debilitating pain that worsens with bending, coughing, or reaching. Because imaging usually looks normal, slipping rib syndrome can go unrecognized for years.
Strained intercostal muscles, the small muscles between adjacent ribs, are another everyday cause. Heavy lifting, violent coughing, or an awkward sleeping position can injure these muscles. The pain is usually reproducible with specific movements and improves with rest and anti-inflammatory medication over one to two weeks.
Stomach, Colon, and Upper-Digestive Causes
The stomach sits partly under the left rib cage, so gastric problems often show up as left-sided upper abdominal pain. Gastritis, which is inflammation of the stomach lining, and gastric ulcers are common offenders. Most gastric ulcers develop because the bacterium H. pylori damages the protective mucous layer that normally shields the stomach lining from its own acid.3Academia.edu. A Detailed Analysis On Acidity And Ulcers In Esophagus, Gastric And Duodenal Ulcers And Management The pain from an ulcer tends to be a burning or gnawing ache that gets worse after eating, and it can radiate toward the back. Overuse of nonsteroidal anti-inflammatory drugs is the other major cause of gastric ulcers, so if you have been taking ibuprofen regularly and develop new left-sided rib pain after meals, that combination is worth mentioning to a doctor.
Gas trapped at the splenic flexure of the colon, the sharp bend the large intestine takes near the spleen before heading downward, can produce a surprisingly intense pain under the left ribs. This is sometimes called splenic flexure syndrome, and it has been described in the medical literature for decades as a recognized pattern of left-sided subcostal discomfort.4Annals of Internal Medicine. Observations on the splenic flexure syndrome The pain often feels like fullness or pressure under the ribs, worsens after large meals or gas-producing foods, and tends to ease after passing gas or having a bowel movement. People who have irritable bowel syndrome are especially prone to it.
Functional dyspepsia, a condition where the upper stomach area hurts despite no visible damage on endoscopy, is another possibility. One theory is that the nerves in the upper gut become hypersensitive, amplifying normal digestive signals into pain.5PubMed Central. Functional dyspepsia: the role of visceral hypersensitivity in its pathogenesis This kind of pain is chronic and recurrent, without the alarming features like weight loss or bleeding that point toward something structural.
Spleen-Related Pain
The spleen sits tucked directly behind the lower left ribs, and when it becomes inflamed, enlarged, or injured, it can produce sharp, unmistakable left upper quadrant pain. In a study of patients with splenic infarction, where part of the spleen’s blood supply gets blocked, severe left upper quadrant pain was the most common symptom at presentation.6PubMed. Splenic infarction: sonographic patterns, diagnosis, follow-up, and complications That said, a good number of splenic infarcts produced no pain at all or presented as vague diffuse abdominal discomfort, which is why this diagnosis sometimes gets missed. Splenic infarcts happen most often in people with blood disorders, atrial fibrillation, or other conditions that increase clotting risk.
Traumatic splenic rupture is more dramatic. A blow to the left side of the abdomen, a fall, or a car accident can tear the spleen, leading to internal bleeding that requires emergency surgery. In one large review, abdominal pain was the dominant complaint, and about a quarter of patients also experienced referred pain in the left shoulder, known as Kehr’s sign, caused by blood irritating the underside of the diaphragm.7The American Journal of Surgery. Traumatic rupture of the spleen Roughly 70 percent of patients developed symptoms within the first 24 hours after injury, but delayed rupture, sometimes days later, does occur, which is why any significant left-sided trauma deserves medical follow-up even if you feel fine at first.
An enlarged spleen from infections like mononucleosis can also cause a dull ache or sense of fullness under the left ribs, even without a dramatic event. Contact sports are restricted during mononucleosis precisely because an enlarged spleen is more vulnerable to rupture from relatively minor impacts.
Kidney Stones and Other Retroperitoneal Causes
The left kidney sits behind the lower ribs toward the back, so a kidney stone on the left side can easily be mistaken for a rib problem, a back injury, or even a spleen issue. Renal colic from a passing stone tends to come on suddenly and severely, with pain radiating from the flank toward the groin.8Synapse (Korean Association of Medical Journal Editors). Ultrasonography of acute flank pain: a focus on renal stones and acute pyelonephritis The pain typically comes in waves, and many people feel restless, unable to find a comfortable position. Nausea and visible blood in the urine are common accompanying signs.
A kidney infection (pyelonephritis) on the left side can also produce pain under and behind the lower ribs, usually accompanied by fever, chills, and painful urination. Unlike a stone, which causes colicky waves, kidney infection pain tends to be more constant and deep, and tapping on the flank often makes it worse. Left-sided kidney pain and left rib-area pain overlap enough in location that urine tests and imaging are sometimes needed to sort them out.
When the Lungs or Diaphragm Are Involved
The left lung and the diaphragm sit directly above the upper abdominal organs, separated by only a thin layer of tissue. Pleurisy, which is inflammation of the membrane surrounding the lung, causes sharp pain that worsens with breathing and can be felt along the left rib cage if the lower portion of the left lung is affected. In fact, pneumonia or pleurisy in the lower left lung can refer pain to the abdomen convincingly enough to mimic a purely abdominal problem.9JAMA. ABDOMINAL PAIN IN PLEURISY AND PNEUMONIA This is a classic clinical pitfall and one reason doctors listen to the lungs even when you come in complaining about belly pain.
A hiatal hernia, where part of the stomach pushes up through the diaphragm into the chest cavity, can cause pain, pressure, or a heavy feeling under the left ribs, especially after meals. Large hiatal hernias have been reported to cause not just typical reflux symptoms but also shortness of breath and chest pain by compressing nearby cardiac structures.10PubMed Central. A Large Intra-Abdominal Hiatal Hernia as a Rare Cause of Dyspnea Most hiatal hernias are small and produce only occasional heartburn, but the larger ones deserve attention because of their potential to cause more widespread symptoms.
Nerve-Related Causes
Intercostal neuralgia is pain originating from one of the nerves that run between the ribs. Trauma, surgery, a tumor pressing on a nerve, or even inflammation from a viral infection can trigger it.11Wiley Online Library / Journal of Medical Imaging and Radiation Oncology. Image-Guided Interventions for Intercostal Neuralgia: What the Radiologist Needs to Know The pain is often described as burning, shooting, or band-like, wrapping around one side of the torso following the path of the affected nerve. It can be confused with heart or lung problems when it involves the left side, particularly because deep breathing or certain postures may aggravate it.
Shingles is a specific and notoriously tricky nerve-related cause. The varicella-zoster virus, which causes chickenpox, can reactivate decades later and inflame a single nerve root. Shingles classically produces excruciating pain followed by the eruption of the characteristic blistering rash along a band of skin.12PubMed Central. Shingles in Pregnancy: An Elusive Case of Left Upper Quadrant Abdominal Pain The problem is that the pain can precede the rash by several days, during which time the cause is invisible and the pain can be mistaken for almost anything, from a heart attack to a kidney stone to a muscle strain. If left-sided rib pain appears suddenly in someone over 50, especially with a burning quality or skin sensitivity, shingles should be on the list even before any rash appears.
Pancreatitis and the Tail of the Pancreas
The tail of the pancreas extends to the left side of the abdomen, and inflammation there, known as pancreatitis, typically produces severe pain in the upper abdomen that radiates straight through to the back. Acute pancreatitis is most often caused by gallstones or heavy alcohol use. The pain tends to be steady, intense, and worse after eating. When it involves the tail of the pancreas more than the head, the pain can be felt more to the left and under the ribs rather than centrally. Chronic pancreatitis can cause milder but recurrent episodes that overlap in location with many of the conditions described above, which makes the clinical history and imaging critical for sorting it out.
Red Flags That Call for Urgent Evaluation
Most left-sided rib pain turns out to be musculoskeletal or digestive and resolves on its own or with simple treatment. But certain features should prompt you to seek medical attention quickly:
- Sudden, severe onset: Pain that hits out of nowhere and takes your breath away, especially after trauma, suggests possible splenic injury, kidney stone, or vascular emergency.
- Shoulder pain with no shoulder injury: Left shoulder pain accompanying left rib pain can indicate diaphragmatic irritation from bleeding or inflammation underneath it, as seen in splenic rupture.
- Fever and chills: These suggest infection, whether in the kidney, lung, or abdomen, and usually warrant blood work and imaging.
- Lightheadedness or fainting: Combined with abdominal pain, these can signal internal bleeding.
- Unexplained weight loss or bloody stool: These “alarm symptoms” point toward conditions that need investigation regardless of where the pain is.
Heart-related pain deserves a mention here even though it is more classically felt behind the breastbone or in the center of the chest. In some people, especially women and older adults, cardiac pain can present atypically, including as discomfort under the left ribs with nausea, sweating, or shortness of breath. When in doubt, err on the side of getting checked.
What Imaging and Testing Can Tell You
If the pain is clearly reproducible by pressing on a specific spot or twisting in a particular way, imaging is usually unnecessary and a clinical exam is enough. For chronic or unexplained abdominal pain, diagnostic imaging is often not needed right away and is frequently overused. A normal CT scan, for instance, does not rule out cancer, and undifferentiated abdominal pain is rarely a good reason for a CT scan on its own.13PubMed Central. Imaging for chronic abdominal pain in adults Ultrasound is usually the first imaging test when spleen or kidney problems are suspected, and it avoids radiation exposure. Blood tests can help identify infection, inflammation, or organ damage. An X-ray may catch a lower-lung pneumonia that is masquerading as abdominal pain. When alarm symptoms are present, such as anemia, blood in the stool, nighttime symptoms that wake you from sleep, or unintentional weight loss, more directed investigation is warranted.
For pain that turns out to be musculoskeletal, diagnosis often rests on the physical exam alone. The “hooking maneuver,” where a doctor hooks their fingers under the lower rib margin and pulls outward, is a classic bedside test for slipping rib syndrome. Costochondritis is diagnosed by reproducing the pain with direct pressure on the rib-cartilage junction. Neither condition shows up on imaging, which is partly why they go unrecognized so often.
Why Left-Sided Rib Pain Gets Misattributed So Often
The left upper quadrant is a crowded neighborhood. The spleen, stomach, colon, pancreatic tail, left kidney, lower left lung, diaphragm, and a web of nerves and muscles all converge in roughly the same space. Pain from one structure can feel identical to pain from another because many of these organs share overlapping nerve pathways. The stomach and the diaphragm, for instance, are both innervated partly by the phrenic nerve, which is why a stomach ulcer and a diaphragmatic hernia can produce eerily similar symptoms.
Referred pain adds another layer of confusion. A kidney stone in the left ureter can cause pain that wraps around to the front of the abdomen. Pneumonia at the base of the left lung can cause pain that feels purely abdominal. And shingles can produce pain along any rib-level nerve band days before a rash makes the diagnosis obvious. Clinicians are trained to think through these overlapping possibilities systematically, but patients searching for answers can help by paying attention to what triggers the pain (eating, breathing, movement, nothing at all), what relieves it, whether it came on suddenly or gradually, and whether any other symptoms like fever, nausea, or changes in bowel habits are present. Those details narrow the field more reliably than the location of the pain alone.