Pain in the left lower abdomen most often comes from the colon, specifically from small pouches in the bowel wall that can become inflamed, a condition called diverticulitis. But several other structures sit in that area of your body, including parts of the small intestine, the left kidney and ureter, and (in women) the left ovary and fallopian tube. Any of these can be the source, and the pattern of your pain, what makes it better or worse, and what other symptoms accompany it all help narrow down the cause.
Diverticulitis: The Most Common Cause
Small bulging pouches called diverticula can form along the wall of the colon, and they tend to develop in the lower left section. Having these pouches is extremely common: roughly 60% of people over age 60 have them. Most people never know they’re there. Problems start when bacteria overgrow at the base of a pouch, causing it to become inflamed or develop tiny tears. That’s diverticulitis, and left lower abdominal pain is the hallmark symptom, present in about 70% of cases.
The pain is typically crampy and may come with fever, nausea, bloating, or a change in your bowel habits, either constipation or looser stools. It often builds over a day or two rather than hitting all at once. Mild cases can be managed at home with rest and a temporary change in diet, while more severe episodes, particularly those involving an abscess or perforation, need closer medical attention. A CT scan of the abdomen is the preferred way to confirm the diagnosis, with a sensitivity above 95% for detecting diverticulitis and its complications.
Irritable Bowel Syndrome and Inflammatory Bowel Disease
If your left-sided pain keeps coming back and tends to coincide with changes in how often you go to the bathroom or what your stool looks like, a functional or inflammatory bowel condition may be involved. Irritable bowel syndrome (IBS) is a functional disorder, meaning the gut looks structurally normal but doesn’t work the way it should. Pain, bloating, and alternating constipation and diarrhea are typical, and symptoms can persist for years before anyone puts a name to them.
Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, involves ongoing inflammation of the intestinal lining. Unlike IBS, IBD causes measurable tissue damage. One way doctors distinguish the two is through a stool marker that reflects intestinal inflammation. Levels below 40 micrograms per gram generally indicate no significant inflammation (pointing toward IBS), while levels above 100 suggest active IBD. The tricky middle zone between those numbers can mean either condition, or IBS that carries a low level of inflammation. A key difference for patients: IBS symptoms often feel disproportionately severe compared to any visible changes in the gut, while IBD can cause visible ulcers and swelling even when symptoms are relatively mild.
Gynecological Causes in Women
In women, the left ovary and fallopian tube sit right next to the lower left colon, so pain in this area isn’t always digestive. Ovarian cysts are fluid-filled sacs that form on or inside the ovary, and most resolve on their own. But a cyst that ruptures or twists (ovarian torsion) causes sudden, sharp pain that can be intense.
Ectopic pregnancy is a more dangerous possibility. This happens when a fertilized egg implants outside the uterus, usually in a fallopian tube. Early warning signs are light vaginal bleeding and pelvic pain. If the tube ruptures, heavy internal bleeding follows, with symptoms like extreme lightheadedness, fainting, and shoulder pain (caused by blood irritating the diaphragm). Ectopic pregnancy is a medical emergency. If you’re of reproductive age and have sudden left-sided pelvic pain with vaginal bleeding or dizziness, get to an emergency room.
Kidney Stones
A stone that forms in your left kidney doesn’t always stay there. As it moves into the ureter, the narrow tube connecting the kidney to the bladder, it can block urine flow and cause the ureter to spasm. The pain typically starts in the flank (your side, just below the ribs) and migrates downward into the lower abdomen and groin as the stone travels. It shifts location and intensity as the stone moves through the urinary tract.
Kidney stone pain is often described as coming in waves and can be severe enough to cause nausea or vomiting. You may also notice blood in your urine or a persistent urge to urinate. The pattern of pain that starts high and moves low, combined with urinary symptoms, helps set kidney stones apart from colon-related causes.
Inguinal Hernia
A hernia in the lower abdomen or groin develops when tissue pushes through a weak spot in the abdominal wall. The most obvious sign is a visible bulge in the groin area that you can sometimes see or feel. It may come and go, sliding back inside when you lie down and reappearing when you stand, cough, or strain. Along with the bulge, you might notice discomfort, heaviness, or a burning sensation in the groin.
Most inguinal hernias aren’t emergencies, but they can become one. If the bulge suddenly gets larger, turns red, or becomes very painful and can’t be pushed back in, the hernia may be trapped (incarcerated) or losing its blood supply (strangulated). That requires urgent surgical attention.
How Doctors Figure Out the Cause
Your doctor will start with your symptom history and a physical exam, pressing on different areas to locate tenderness and checking for any bulges or masses. From there, the most common next step for left lower abdominal pain is a CT scan. The American College of Radiology recommends CT as the initial imaging test for this type of pain because it’s highly accurate for detecting diverticulitis, abscesses, bowel obstruction, and other structural problems. Ultrasound is sometimes used, particularly when a gynecological cause is suspected, though its sensitivity for diverticulitis is lower and more variable than CT. MRI is an option when radiation exposure is a concern, with sensitivity in the 86% to 94% range for diverticulitis.
Blood and stool tests can help determine whether inflammation or infection is present, and urine tests can point toward kidney stones or a urinary tract infection. In many straightforward cases of diverticulitis, doctors make the diagnosis based on symptoms and exam findings alone, reserving imaging for situations where the diagnosis is uncertain or complications are suspected.
Signs That Need Immediate Attention
Most causes of left lower abdominal pain aren’t emergencies, but some are. Sudden, severe pain that comes on quickly and doesn’t let up warrants a call to emergency services. So does pain that gets dramatically worse when you lightly touch the area or bump into something, which can signal inflammation spreading to the lining of the abdominal cavity. Other red flags include a rapid heart rate, low blood pressure, sweating, confusion, fainting, or heavy vaginal bleeding. These can indicate internal bleeding, a ruptured organ, or sepsis, all of which are time-sensitive.
Pain that’s been present for a few days, feels more like a dull ache or cramp, and isn’t getting worse is less likely to be an emergency. But persistent or recurring pain that disrupts your daily life still deserves a medical evaluation, even if it doesn’t feel urgent. Many of the conditions behind left lower abdominal pain are very treatable once identified.