Pain in the lower left abdomen most commonly comes from the digestive tract, specifically the sigmoid colon and descending colon, which sit in that area. But depending on your age, sex, and other symptoms, the cause could range from a mild muscle cramp to something that needs prompt medical attention. Here’s a breakdown of the most likely causes and how to tell them apart.
Diverticulitis
Diverticulitis is the single most common cause of significant lower left abdominal pain in adults over 40. Small pouches called diverticula form along the colon wall over time, and when one becomes inflamed or infected, it triggers sudden, dull pain in the lower left abdomen along with a mild fever. You may also notice constipation, diarrhea, bloating, nausea, or cramping.
The exact reason diverticula become inflamed isn’t fully understood, but it likely involves reduced blood supply to the pouch or hard stool getting trapped inside it. One telltale sign: if you press on the painful area and then quickly release, the pain briefly gets worse. Mild cases are treated with rest and antibiotics, while more severe episodes with high fever or persistent vomiting may need hospital care.
Irritable Bowel Syndrome
IBS frequently causes pain in the lower left abdomen because the sigmoid colon, the S-shaped final stretch of the large intestine, is prone to strong circular contractions in people with this condition. Research using pressure recordings has confirmed that these contractions directly correspond to the cramping pain IBS patients describe. The pain tends to come and go, often improving after a bowel movement, and is usually accompanied by changes in stool consistency or frequency. Unlike diverticulitis, IBS doesn’t cause fever or signs of infection.
Ulcerative Colitis
Ulcerative colitis is a chronic inflammatory bowel disease that often starts in the rectum and extends upward into the sigmoid and descending colon. When inflammation is limited to this left side, it’s called left-sided colitis, and it causes bloody diarrhea, belly cramps, and a frustrating sensation called tenesmus, where you feel the urge to have a bowel movement but can’t pass anything. The pain tends to be persistent rather than episodic, and symptoms typically worsen over weeks rather than appearing overnight. If you’re seeing blood in your stool alongside recurring left-sided pain, this is one of the conditions your doctor will want to rule out.
Ovarian Cysts
For women and people with ovaries, a cyst on the left ovary is a common cause of lower left abdominal pain. Most ovarian cysts are harmless and disappear without treatment, but larger ones can produce a dull ache or sharp pain below and to one side of the bellybutton, along with bloating, fullness, or a feeling of pressure in the abdomen. The pain often comes and goes.
Two complications make ovarian cysts more urgent. A large cyst can cause the ovary to twist (ovarian torsion), which produces sudden, severe pelvic pain with nausea and vomiting. A cyst can also rupture, causing intense pain and internal bleeding. Vigorous physical activity, including sex, increases the risk of rupture. Sudden, severe pain on one side that comes with vomiting, fever, or signs of shock (cold skin, rapid breathing, lightheadedness) is a reason to get immediate help.
Kidney Stones
A stone that forms in the left kidney doesn’t always stay there. When it moves into the ureter, the narrow tube connecting the kidney to the bladder, it can block urine flow, cause the kidney to swell, and trigger intense referred pain that radiates into the lower abdomen and groin. This pain is distinctive: it comes in waves, fluctuating between sharp spikes and duller aches, and it’s often accompanied by a burning sensation when urinating. You might also notice pink, red, or brown urine. Kidney stone pain rarely stays constant. It shifts and intensifies as the stone moves.
Inguinal Hernia
An inguinal hernia occurs when tissue pushes through a weak spot in the abdominal wall near the groin. It’s far more common in men, though women can develop them too. The hallmark sign is a visible or palpable bulge in the groin area, accompanied by discomfort, heaviness, or a burning sensation. In men, the bulge may extend into the scrotum. Symptoms typically worsen when you strain, lift, cough, or stand for long periods, and improve when you lie down. A hernia that can’t be pushed back into place, or one that comes with sudden sharp pain and nausea, may be strangulated, meaning its blood supply is cut off, and that requires emergency surgery.
Epiploic Appendagitis
This is a lesser-known cause that often gets mistaken for diverticulitis. Small fat-filled pouches hang off the outside of the colon, and when one loses its blood supply, it becomes inflamed and causes sudden, localized pain you can pinpoint with a finger. The good news is that epiploic appendagitis resolves on its own. The affected pouch eventually calcifies and breaks off, ending the inflammation. Treatment is limited to pain relief while your body handles the rest. It’s worth knowing about because imaging can distinguish it from more serious conditions, potentially sparing you unnecessary antibiotics or surgery.
How to Tell What’s Serious
Mild, short-lived pain in the lower left abdomen is common and often resolves without treatment. Gas, constipation, menstrual cramps, and muscle strains can all cause temporary discomfort in this area. The character of the pain and the symptoms that accompany it are what separate routine from concerning.
Pain that keeps coming back, mild pain that has gradually worsened over days or weeks, or pain paired with any of the following warrants a call to your doctor: fever or chills, blood in your stool or urine, vomiting blood, yellowing of the skin or eyes, inability to pass gas or have a bowel movement, or shortness of breath. Severe pain that comes on suddenly, especially with vomiting or signs of shock, is a reason to go to the emergency room rather than waiting for an appointment.
Because so many different organs and structures sit in the lower left abdomen, your doctor will likely ask detailed questions about when the pain started, what makes it better or worse, and what other symptoms you’ve noticed. Imaging with ultrasound or a CT scan is often the next step, particularly if the physical exam doesn’t point clearly to one cause. The combination of your symptom pattern, lab work, and imaging is usually enough to narrow it down.