Pain on the left side of your abdomen can come from dozens of different structures, from the intestines and kidney to muscles in the abdominal wall. The most common cause in adults is diverticulitis, especially if the pain is in the lower left area. But several other conditions, some minor and some urgent, produce pain in the same region. Understanding where the pain falls, how it feels, and what other symptoms come with it helps narrow the list.
Your left abdomen contains different organs depending on whether the pain is higher or lower. The upper left houses the spleen, stomach, body of the pancreas, left kidney, adrenal gland, and part of the colon. The lower left contains the descending and sigmoid colon, the left ureter, and in women, the left ovary and fallopian tube. Pain can also originate from the abdominal wall itself rather than an internal organ.
Diverticulitis
Diverticulitis is the single most likely diagnosis when pain centers on the lower left abdomen. Small pouches called diverticula form in weak spots of the colon wall, often from years of pressure during bowel movements. These pouches are common after age 50. When one or more of them become inflamed or infected, the result is sudden, often intense pain below the navel on the left side. The pain can also start mild and gradually worsen, or fluctuate in intensity over hours.
Along with the pain, diverticulitis frequently causes fever, nausea, tenderness when the area is touched, and a noticeable change in bowel habits like sudden diarrhea or constipation. While diverticulitis has traditionally been considered a condition of older adults, serious cases are rising sharply among people under 50. An analysis of more than 5.2 million hospitalizations between 2005 and 2020 found that the share of patients under 50 admitted with severe complications jumped from 18.5% to 28.2%. Younger patients were also 29% more likely to need surgery and 58% more likely to need a catheter drainage procedure compared to older patients.
Kidney Stones
A stone forming in or passing through the left kidney or ureter produces pain that typically starts in the lower back or flank and radiates toward the groin. The sensation is often described as waves of sharp, intense pain (sometimes called renal colic) that come and go. Between waves, you might feel a dull ache. As the stone moves down the ureter toward the bladder, the location of the pain shifts lower, which is why it can easily be confused with a problem in the intestines or reproductive organs. Blood in the urine, nausea, and an urgent need to urinate are common accompanying signs.
Gas, Constipation, and Irritable Bowel Syndrome
Not every left-sided pain points to something serious. Trapped gas in the descending colon or the sharp bend of the colon near the spleen (the splenic flexure) can produce surprisingly sharp, cramp-like pain in the upper or lower left abdomen. Constipation tends to cause discomfort on the left because stool accumulates in the descending and sigmoid colon before reaching the rectum. Irritable bowel syndrome often produces recurrent cramping on the left side, along with bloating and alternating diarrhea and constipation. These conditions are generally manageable with dietary changes and don’t cause fever or blood in the stool.
Spleen Problems
The spleen sits behind your lower ribs on the left side. When it becomes enlarged from infection, liver disease, or a blood disorder, it can cause a dull ache or feeling of fullness in the upper left abdomen. A more dangerous situation is a splenic infarction, where blood flow to part of the spleen gets blocked and tissue dies. This causes sudden, severe pain in the upper left belly that may radiate to the left shoulder. Splenic infarctions are associated with blood cancers like leukemia and lymphoma, clotting disorders such as sickle cell disease, and heart conditions like atrial fibrillation that produce clots. Abdominal trauma from a fall or car accident can also injure the spleen.
Gynecological Causes
In women, left-sided lower abdominal pain has an additional set of possibilities because the left ovary and fallopian tube sit in that area. An ovarian cyst that ruptures or twists (ovarian torsion) causes sudden, sharp pelvic pain on the affected side. Endometriosis can produce chronic, recurring pain that worsens around menstruation.
The most dangerous gynecological cause is an ectopic pregnancy, where a fertilized egg implants in the fallopian tube instead of the uterus. Early signs often mimic a normal early pregnancy: a missed period, breast tenderness, and nausea. The first warning of trouble is usually light vaginal bleeding and pelvic pain. If the tube ruptures, you may feel shoulder pain, extreme lightheadedness, or faintness. This is a life-threatening emergency. Severe pelvic pain with vaginal bleeding, fainting, or shoulder pain requires immediate emergency care.
Hernias
A hernia occurs when an organ or tissue pushes through a weak spot in the muscle wall that normally contains it. In the left lower abdomen or groin, an inguinal hernia is most common, caused by part of the bowel protruding through the inguinal canal in the inner thigh. The hallmark sign is a visible bulge that appears when you strain, lift, cough, or laugh, then disappears when you relax or lie down. You may also feel pressure, a dull ache, or a pinching sensation when the hernia comes out.
Hernias become serious when the protruding tissue gets trapped and can’t slide back in. This cuts off blood supply and can lead to tissue death, causing escalating pain, nausea, and sometimes fever.
Less Common but Serious Causes
Heart disease can sometimes masquerade as upper abdominal pain. A heart attack may present as severe nausea or pain under the left rib cage rather than classic chest pain, particularly in women and older adults. An abdominal aortic aneurysm, a dangerous widening of the body’s largest artery, usually causes no symptoms until it begins leaking or ruptures. At that point, it produces sudden, severe belly or back pain that feels like ripping or tearing. Both of these are medical emergencies.
How Doctors Figure Out the Cause
Your doctor will start with the basics: where exactly the pain is, how it started, how it feels, and what other symptoms you have. Blood work and a urine test help check for infection, kidney problems, and pregnancy. For left lower quadrant pain, a CT scan is the recommended first imaging test because it can identify diverticulitis, kidney stones, hernias, and many other causes in a single study. If a gynecological cause is suspected in a woman of reproductive age, pelvic ultrasound is preferred. For pregnant patients, ultrasound or MRI is used instead of CT to avoid radiation.
Signs That Need Emergency Attention
Most left-sided abdominal pain turns out to be something treatable and non-life-threatening. But certain combinations of symptoms warrant an emergency room visit rather than waiting for a routine appointment:
- Severe pain that makes it difficult to move, eat, or drink
- Sudden onset of intense pain that wasn’t building gradually
- High fever alongside abdominal pain
- Blood in your stool or vomit
- Pain after trauma to the abdomen, such as a fall or car accident
- Extreme lightheadedness or fainting, especially with pelvic pain and vaginal bleeding
Upper abdominal pain under the rib cage with nausea should also be taken seriously, since it can be a sign of a cardiac event rather than a digestive problem.