Pain in the lower left side of your abdomen usually comes from the digestive tract, most commonly the sigmoid colon, which is the S-shaped section of your large intestine that sits in that exact area. The cause can range from trapped gas or constipation to conditions like diverticulitis or irritable bowel syndrome. For women, the left ovary and fallopian tube also live in this region, adding gynecological causes to the list.
What’s causing your pain depends on how it feels, how long it’s lasted, and what other symptoms come with it. Here’s a breakdown of the most likely explanations.
Gas, Constipation, and Muscle Spasms
The most common and least worrisome cause is simply gas or stool building up in the descending and sigmoid colon. Your large intestine makes a sharp bend on the left side (called the splenic flexure), and gas tends to get trapped there. If you’re constipated, hard stool sitting in the sigmoid colon creates pressure and cramping in exactly this spot. The pain often feels dull and achy, comes and goes, and improves after you pass gas or have a bowel movement.
Muscle strain is another overlooked possibility. If you’ve recently exercised, twisted, or lifted something heavy, the abdominal wall muscles on that side can be sore. This type of pain typically gets worse when you move, cough, or tense your core, and feels more like a pulled muscle than deep internal pressure.
Irritable Bowel Syndrome (IBS)
IBS is one of the most common reasons for recurring left-sided abdominal pain, especially in people under 50. The intestinal muscles contract longer and harder than normal, causing cramping and pain that’s closely tied to bowel movements. You might notice the pain eases after you go to the bathroom, or that it flares alongside diarrhea, constipation, or both.
People with IBS also have oversensitive nerve endings in the digestive tract. Small bubbles of gas that wouldn’t bother most people can be genuinely painful. This heightened sensitivity leads to bloating and swelling that tends to concentrate on the left side, where the colon is most active in moving stool toward the rectum. IBS pain is typically crampy rather than sharp, and it rarely wakes you from sleep or causes fever.
Diverticulitis
Diverticulitis is the hallmark diagnosis for sudden, significant pain in the lower left abdomen, particularly in adults over 40. Small pouches (diverticula) form along the wall of the colon over time, and when one becomes inflamed or infected, the result is localized pain that can range from mild and gradually worsening to sudden and intense. Fever, nausea, and changes in bowel habits (sudden constipation or diarrhea) often accompany it, and the area feels tender when pressed.
Mild cases can sometimes be managed without antibiotics, with rest and a temporary shift to easier-to-digest foods. More complicated cases involving abscesses or blockages may need antibiotics, drainage procedures, or in 15 to 32 percent of hospitalized cases, emergency surgery. After recovery from a complicated episode, a colonoscopy is typically recommended to confirm the diagnosis and rule out colon cancer, which can mimic diverticulitis. Reducing red meat intake, staying physically active, maintaining a healthy weight, and quitting smoking all lower the risk of future flare-ups.
Inflammatory Bowel Disease
Ulcerative colitis and Crohn’s disease both cause belly pain and cramping, often alongside diarrhea, rectal bleeding, extreme fatigue, and weight loss. Ulcerative colitis affects the colon and rectum, so left-sided pain is common as the disease often starts in the sigmoid colon and spreads upward. Crohn’s disease can affect any part of the digestive tract but sometimes involves the left colon as well.
One distinctive feature of Crohn’s disease is the potential for strictures, areas where the intestine narrows from repeated inflammation. High-fiber or bulky foods can get stuck at these narrowings, causing sudden pain, vomiting, and loud gurgling sounds in the abdomen. If your lower left pain is paired with bloody stool, unintended weight loss, or fatigue that won’t go away, inflammatory bowel disease is worth investigating.
Causes Specific to Women
The left ovary and fallopian tube sit in the lower left abdomen, so several gynecological conditions can produce pain in this area. Ovarian cysts are fluid-filled sacs that form on the ovary, and most resolve on their own. But larger cysts or endometriomas (cysts caused by endometriosis) produce pelvic pain or tenderness that can happen at any time, not just during your period. You might also notice painful periods, discomfort during sex, pain while urinating or having a bowel movement, bloating, or back pain.
Ovarian torsion, where the ovary twists on its supporting tissue, causes sudden, severe one-sided pain and is a surgical emergency. A ruptured endometrioma can produce similar sudden pain along with fever, weakness, nausea, and vomiting. Ectopic pregnancy, where a fertilized egg implants in the left fallopian tube, is another emergency that causes sharp lower left pain, sometimes with vaginal bleeding and dizziness.
Causes Specific to Men
Inguinal hernias are a leading cause of lower abdominal and groin pain in men. They occur when tissue pushes through a weak spot in the lower abdominal wall near the groin. The telltale sign is a visible bulge that may extend into the scrotum, accompanied by discomfort, heaviness, or a burning sensation. Symptoms typically worsen when you strain, lift, cough, or stand for long periods, and improve when you lie down.
A hernia that becomes trapped (incarcerated) or loses its blood supply (strangulated) is a medical emergency. Warning signs include a bulge that suddenly gets larger, can no longer be pushed back in, or becomes red and severely painful, along with fever, nausea, or vomiting.
Kidney Stones
A stone in the left kidney or ureter can produce pain that starts in the mid-back and side, then radiates forward below the rib cage and down into the groin. This referred pain can feel like it’s coming from the lower left abdomen. Kidney stone pain is often intense and comes in waves, and it’s usually accompanied by painful urination, blood in the urine, or an urgent need to urinate. If your pain started in your back or flank before moving forward, a kidney stone is a strong possibility.
How Doctors Figure Out the Cause
When the cause isn’t obvious from your symptoms alone, imaging helps narrow things down. A CT scan of the abdomen and pelvis with contrast is the recommended first-line imaging test for left lower quadrant pain. It has over 95% sensitivity for detecting diverticulitis and can also reveal other conditions that look similar, such as inflammatory bowel disease, abscesses, or tumors. Ultrasound is sometimes used, particularly for gynecological causes, but its accuracy varies more depending on the operator and body type.
For many cases of mild, short-lived pain, no imaging is needed at all. Your doctor will press on the area, ask about your bowel habits and other symptoms, and may order basic blood work to check for infection or inflammation.
When Left-Sided Pain Is an Emergency
Sudden, severe abdominal pain that comes on without warning should never be brushed off. Seek immediate care if your pain is accompanied by vomiting blood or material that looks like coffee grounds, black or tarry stool, blood in your stool, high fever, or a rigid abdomen that’s exquisitely tender to touch. Severe pain that radiates through to your back, groin, or legs, especially with faintness or nausea, can signal a ruptured abdominal aortic aneurysm, which is life-threatening. Pain that started mild and is steadily getting worse over hours also warrants urgent evaluation, as it may indicate a developing infection, obstruction, or torsion.