Left-sided abdominal pain has dozens of possible causes, ranging from trapped gas that resolves in hours to conditions like diverticulitis or kidney stones that need medical treatment. Where exactly the pain sits, how it feels, and what other symptoms come with it are the biggest clues to what’s going on.
Your left abdomen contains different organs depending on whether the pain is higher up (near and below your ribs) or lower down (below your navel). Narrowing down the location is the single most helpful thing you can do before deciding on next steps.
What’s on the Left Side of Your Abdomen
The left upper area houses your stomach, spleen, pancreas, part of your colon, and the upper portion of your left kidney. The left lower area contains the lower colon (sigmoid colon), the lower portion of your left kidney, the left ureter, and, in women, the left ovary and fallopian tube. Pain doesn’t always stay neatly inside these zones, but knowing what’s there helps make sense of the possibilities below.
Lower Left Pain: The Most Common Causes
Gas and Constipation
The most likely explanation for mild to moderate lower left pain is also the least serious. Gas tends to collect in the bends of the colon, and the left side has a sharp turn (the splenic flexure) where gas frequently gets trapped. This pain is usually crampy, moves around, and improves after passing gas or having a bowel movement. Constipation creates a similar ache, often with bloating and a sense of fullness. If the pain comes and goes, doesn’t wake you from sleep, and isn’t accompanied by fever or vomiting, gas or constipation is the likely culprit.
Diverticulitis
Diverticulitis is the most common serious cause of lower left abdominal pain, especially in adults over 40. It happens when small pouches that form in the colon wall become inflamed or infected. The pain is typically moderate to severe, and you can usually point to the exact spot that hurts. It may feel sharp and penetrating or have a burning quality. An acute attack comes on suddenly, while a chronic flare builds over a few days.
Unlike gas pain, diverticulitis usually brings additional symptoms: fever, nausea, vomiting, constipation (or less commonly diarrhea), and sometimes a visibly swollen abdomen. The pain doesn’t shift around the way gas does. It stays in one place and gets worse rather than better over time. If you also notice fresh blood in your stool, feel weak or pale, have frequent or painful urination, or your abdomen feels rigid and tender to the lightest touch, those are signs of complications that need urgent care.
Kidney Stones
A stone moving through your left kidney or ureter can cause pain anywhere from your lower left abdomen to your flank (the area between your ribs and hip on your back) to your groin. The pain often comes in intense waves, sometimes called colicky pain, and can shift location as the stone moves. It may be a dull ache or sharp and severe. Nausea, blood-tinged urine, and an urgent need to urinate are common alongside it. If the pain is more in your side or back and radiates downward, a kidney stone is worth considering.
Ovarian Cysts and Torsion (Women)
Most ovarian cysts form and dissolve without you ever knowing, but a large cyst on the left ovary can cause a dull ache or sharp pain below your navel on one side, along with bloating, fullness, or pelvic pressure. The pain often comes and goes. A ruptured cyst causes a sudden, sharper pain that may spread across the pelvis.
Ovarian torsion, where the ovary twists on its blood supply, is rarer but more dangerous. It produces sudden, severe pelvic pain with nausea and vomiting. This is an emergency because the twist can cut off blood flow to the ovary.
Upper Left Pain: What to Consider
Pain in the upper left abdomen, near or just under the ribs, points to a different set of organs. Gastritis or a stomach ulcer can cause a burning or gnawing pain in this area, often worse after eating or on an empty stomach. Pancreatitis produces a deep, boring pain in the upper abdomen that frequently radiates to the back and worsens after meals, especially fatty ones.
An enlarged spleen causes pain or a sense of fullness in the left upper belly that can spread to the left shoulder. You might feel full after eating only a small amount because the swollen spleen presses on your stomach. Pain that worsens when you take a deep breath is a notable feature. Spleen enlargement has many underlying causes, from infections to blood disorders, so it’s always worth getting evaluated.
Muscle and Abdominal Wall Pain
Not all left-sided pain comes from inside the abdomen. Strained muscles, a pinched nerve, or even a condition called slipping rib syndrome can mimic organ pain. A strong clue that the pain is in your abdominal wall rather than your organs: you can point to the exact sore spot with one fingertip, and the pain stays the same or gets worse when you tense your abs (like doing a partial sit-up). Organ pain, by contrast, typically feels deeper, is harder to pinpoint, and often improves or doesn’t change when you flex the muscles over it.
If you recently exercised hard, lifted something heavy, or had a bout of intense coughing, a muscle strain is a reasonable explanation. This kind of pain is usually positional, meaning it changes with movement, and doesn’t come with fever, nausea, or changes in your bowel habits.
How to Tell Gas Pain From Something Serious
The overlap between harmless gas and conditions like diverticulitis can be confusing at first, but there are practical differences. Gas pain is crampy, shifts location, improves with movement or passing gas, and doesn’t bring a fever. Diverticulitis pain is fixed in one spot, moderate to severe, and typically accompanied by fever, nausea, or changes in bowel habits. Pain that steadily worsens over hours, wakes you from sleep, or comes with a temperature above 100.4°F (38°C) is unlikely to be gas.
Another useful distinction: gas and bloating usually peak after meals or at the end of the day and feel better in the morning. Inflammatory conditions like diverticulitis or colitis don’t follow that pattern. They persist or worsen regardless of what you eat or what time it is.
When Left Abdominal Pain Is an Emergency
Sudden, severe abdominal pain that comes on quickly is sometimes called an “acute abdomen” and may require urgent treatment or even surgery. Call emergency services or go to an ER if you experience any of the following alongside your left-sided pain:
- Rigid abdomen that is extremely sensitive to even light touch or a gentle bump
- Signs of shock such as rapid heart rate, sweating, confusion, or feeling faint
- Significant swelling where your abdomen looks visibly larger than normal
- High fever with vomiting that prevents you from keeping fluids down
- Blood in your stool or vomit
These symptoms can signal perforation (a hole in the bowel), peritonitis (infection of the abdominal lining), or internal bleeding. They are rare, but they’re the reason severe, worsening abdominal pain should never be waited out.
What Happens When You Get It Checked
For lower left abdominal pain, a CT scan of the abdomen and pelvis with contrast is the most useful test. It has about 98% diagnostic accuracy for diverticulitis and is also good at catching alternative diagnoses that present similarly. Ultrasound is used in some settings, particularly in Europe, but it’s less accurate overall, especially in patients with a higher body weight or when complications are present. For upper left pain, blood work and imaging (CT or ultrasound depending on the suspected cause) are standard starting points.
If the pain is mild, came on gradually, and you have no fever or alarming symptoms, it’s reasonable to monitor it for a day or two while sticking to bland foods and staying hydrated. Pain that persists beyond 48 hours, gets progressively worse, or develops any of the red flags above warrants a medical evaluation rather than a wait-and-see approach.