Pain in the lower left side of your stomach most commonly comes from your digestive system, specifically the sigmoid colon, which is the S-shaped segment of your large intestine that sits in that exact spot. But several other structures live in this area too, including the left ovary and fallopian tube in women, the left ureter (the tube connecting your kidney to your bladder), and the lower portion of the descending colon. The cause of your pain depends on what the pain feels like, how long it’s lasted, and what other symptoms you’re experiencing.
Gas and Constipation: The Most Common Culprits
The sigmoid colon is the last major stop before stool reaches the rectum, which makes it a common place for gas to get trapped and stool to back up. If your pain is crampy, comes and goes, and gets better after passing gas or having a bowel movement, constipation or trapped gas is the most likely explanation. Bloating and a feeling of fullness on the left side are typical.
If constipation is the issue, the best-supported options for relief are polyethylene glycol (the active ingredient in MiraLAX) and senna, both of which have strong clinical evidence behind them. Fruits like kiwi, prunes, and mangoes also have moderate evidence supporting their effectiveness. Fiber supplements like psyllium are commonly recommended, but the evidence is actually mixed. In direct comparison trials, psyllium was less effective than prunes or mangoes for relieving constipation. Stool softeners containing docusate, despite being widely used, have essentially no good evidence supporting them.
Diverticulitis
Diverticulitis is one of the most important causes to know about. It happens when small pouches that form in the wall of the colon become inflamed or infected. Left lower abdominal pain is the most common symptom, showing up in about 70% of cases. The pain is typically crampy and may come with fever, nausea, vomiting, constipation, bloating, or a noticeable change in your bowel habits.
These pouches (called diverticula) are extremely common, especially as people age, but only about 4% of people who have them ever develop diverticulitis. When diverticulitis is mild, it can sometimes be managed at home with a clear liquid diet for a few days, followed by a gradual return to regular food. Most people with mild cases start feeling better within two to three days. If the pain doesn’t improve in that window, that’s a sign something more is going on.
When diverticulitis is suspected, a CT scan is the standard diagnostic tool. It can confirm the diagnosis, identify complications like abscesses or perforations, and rule out other causes of the pain. If a CT scan isn’t available or isn’t appropriate, ultrasound or MRI are alternatives.
Irritable Bowel Syndrome
IBS can produce chronic or recurring pain in the lower left abdomen that closely mimics other conditions, including diverticulitis. The hallmark pattern is abdominal pain that improves after a bowel movement, along with changes in how often you go or what your stool looks like. Constipation alternating with diarrhea, gassiness, bloating, mucus in the stool, and the urgent feeling that you need to go without actually being able to are all characteristic.
Symptoms tend to flare after large meals or during periods of stress. Unlike inflammatory bowel disease (conditions like ulcerative colitis or Crohn’s disease), IBS does not cause visible damage to the intestines. There’s no inflammation, no bleeding, and imaging tests come back looking normal. If you’re experiencing weight loss, blood in your stool, anemia, or fever alongside your pain, those are signs of something other than IBS and need prompt evaluation.
Kidney Stones
A stone moving through the left ureter can produce pain that radiates into the lower left abdomen and groin, even though the stone itself is in your urinary tract. This pain tends to be severe and sharp, starting in the side or back below the ribs and spreading downward. It characteristically comes in waves, shifting in location and intensity as the stone moves. You may also notice pain with urination, blood-tinged urine, or nausea. If the pain is sudden, intense, and wave-like, a kidney stone is worth considering even if the location seems more like a stomach problem.
Causes Specific to Women
In women, the left ovary and fallopian tube sit in the lower left quadrant, adding several possible explanations. Ovarian cysts are fluid-filled sacs that form on or inside the ovary. Larger cysts cause pelvic pain or a dull ache in the lower back, along with a feeling of fullness or bloating that’s more noticeable on one side. If a cyst ruptures, the pain is sudden, sharp, and usually intense.
Endometriosis can also cause left-sided pelvic pain, particularly when tissue similar to the uterine lining grows on or near the left ovary, forming what are called endometriomas (sometimes referred to as chocolate cysts because of their dark, blood-filled appearance). This pain often worsens around your period. An ectopic pregnancy, where a fertilized egg implants in the left fallopian tube instead of the uterus, is a medical emergency that causes sharp, one-sided pelvic pain, sometimes with vaginal bleeding or dizziness.
Inguinal Hernias
An inguinal hernia occurs when tissue from inside the abdomen pushes through a weak spot in the lower abdominal wall near the groin. Men are 8 to 10 times more likely than women to develop one. Symptoms include a visible bulge in the groin area (or in the scrotum in men), along with discomfort, pain, heaviness, or a burning sensation. The pain often gets worse with coughing, bending, or lifting. Hernias develop more frequently on the right side, but left-sided hernias are common enough that they’re worth considering if your pain is near the groin and you notice a bulge.
Signs That Need Immediate Attention
Most lower left abdominal pain turns out to be something manageable, but certain combinations of symptoms point to something more serious. A fever above 99.5°F (37.5°C) with abdominal pain raises the concern for infection or inflammation that may need treatment. Rebound tenderness, where the pain gets sharply worse when you press on your abdomen and then release, suggests irritation of the abdominal lining. A rigid, board-like abdomen that you can’t relax is another red flag.
Blood in your stool, inability to pass gas or have a bowel movement at all, severe pain that’s getting steadily worse rather than coming and going, vomiting that won’t stop, or signs of shock like lightheadedness and a rapid heartbeat all warrant emergency evaluation. For women of childbearing age, sudden sharp pelvic pain with missed periods or unusual bleeding should be treated as urgent until an ectopic pregnancy is ruled out.