Pain in the left lower abdomen most commonly comes from a digestive issue, particularly diverticulitis in adults over 50 or irritable bowel syndrome in younger adults. But several other conditions, from muscle strains to kidney stones to reproductive organ problems, can cause pain in this exact spot. The cause depends on the type of pain you’re feeling, how suddenly it started, and what other symptoms came with it.
Diverticulitis: The Most Common Cause
Diverticulitis is the single most common reason adults develop pain specifically in the left lower abdomen. It happens when small pouches that form in the wall of the colon become inflamed or infected. These pouches, called diverticula, develop where the colon wall is weakest, often from years of pressure during bowel movements. The pouches themselves are harmless and extremely common after age 50. Problems start when bacteria infect them or the tissue gets damaged, triggering inflammation that brings increased blood flow, swelling, and pain.
The pain usually comes on suddenly and feels intense, though it can also start mild and build over several days. You may also notice fever, nausea, tenderness when you press on the area, and changes in your bowel habits like sudden diarrhea or constipation. Mild cases sometimes resolve with rest and a temporary change in diet, and recent clinical guidelines suggest that not all patients with uncomplicated diverticulitis even need antibiotics. More severe cases, especially those with complications like an abscess, do require medical treatment.
If your doctor suspects diverticulitis, a CT scan of the lower abdomen and pelvis with IV contrast is the standard imaging test. People with a clear history of diverticulitis who are experiencing a familiar recurrence may not need imaging at all and can sometimes be treated based on symptoms alone.
Irritable Bowel Syndrome and Inflammatory Bowel Disease
Two other digestive conditions frequently cause left-sided abdominal pain: irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). They share some symptoms but work very differently in the body.
IBS causes abdominal pain and cramping along with diarrhea, constipation, or both. The underlying cause isn’t fully understood, but the symptoms appear to stem from uncoordinated contractions in the intestines and hypersensitive nerves in the gut. There’s no visible damage to the digestive tract. Pain from IBS tends to come and go, often worsening with stress or after eating, and it frequently improves after a bowel movement.
IBD, which includes conditions like ulcerative colitis and Crohn’s disease, involves the immune system attacking the lining of the digestive tract, causing chronic inflammation. Symptoms include abdominal pain and cramping, but also fevers, diarrhea, and bloody bowel movements. If you’re seeing blood in your stool alongside persistent left-sided pain, that distinction matters and points toward IBD rather than IBS.
Kidney Stones
A stone that forms in the left kidney can cause pain in the left lower abdomen, especially once it moves out of the kidney and into the ureter, the narrow tube connecting the kidney to the bladder. A stone sitting quietly in the kidney often causes no symptoms at all. The pain starts when the stone gets stuck, blocking urine flow and causing the kidney to swell and the ureter to spasm.
Kidney stone pain is hard to mistake for anything else. It tends to come in intense waves, and you may also notice blood in your urine, nausea, vomiting, fever, or chills. The pain often radiates from your side or back down toward your lower abdomen and groin. If you’re experiencing sharp, wave-like pain that shifts location and comes with urinary changes, a kidney stone is a strong possibility.
Inguinal Hernia
A hernia on the left side can cause pain in the lower abdomen near the groin. An inguinal hernia happens when tissue, usually part of the intestine, pushes through a weak spot in the abdominal wall. The hallmark sign is a visible bulge near the pubic bone that becomes more obvious when you stand up, cough, or strain. You can often feel it by placing your hand directly over the area.
The pain tends to worsen with specific movements: bending over, coughing, or lifting something heavy. You might also feel a burning or aching sensation at the site of the bulge. In men, pain and swelling can extend down into the scrotum if the protruding tissue descends that far. Hernias don’t resolve on their own and typically require surgical repair, especially if they’re causing pain or growing larger.
Reproductive Organ Causes in Women
For women, the left lower abdomen sits directly over the left ovary and fallopian tube, which means reproductive conditions often show up as pain in this area.
Ovarian cysts are fluid-filled sacs that develop on or in an ovary. Most are harmless and resolve without treatment, but larger cysts or those that rupture can cause sharp, sudden pain on the affected side. The pain may come with bloating or a feeling of fullness in the pelvis.
Endometriosis causes tissue similar to the uterine lining to grow outside the uterus. The most common symptom is pelvic pain that goes beyond normal menstrual cramping, either during or outside of your period. Pain with bowel movements or urination is also common, particularly right before or during menstruation. Heavy periods, bleeding between periods, and difficulty getting pregnant are other signs. Endometriosis can sometimes cause cysts on the ovaries as well, which adds another layer of pain. Because its symptoms overlap significantly with ovarian cysts and pelvic inflammatory disease, it often takes time to get an accurate diagnosis.
Ectopic Pregnancy
If you could be pregnant and are experiencing left lower abdominal pain, ectopic pregnancy needs to be ruled out. This occurs when a fertilized egg implants outside the uterus, most often in a fallopian tube. Early warning signs include light vaginal bleeding and pelvic pain, sometimes alongside typical pregnancy symptoms like a missed period, breast tenderness, and nausea.
As the ectopic pregnancy progresses, it can cause the fallopian tube to rupture, leading to heavy internal bleeding. Symptoms of rupture include extreme lightheadedness, fainting, and shock. Some women also feel shoulder pain or a sudden urge to have a bowel movement as leaking blood irritates nearby nerves. Severe abdominal or pelvic pain with vaginal bleeding, extreme dizziness, or shoulder pain all warrant emergency care immediately. This is a life-threatening situation that requires rapid treatment.
Muscle Strain
Not every left lower abdominal pain has an internal cause. A pulled or strained muscle in the abdominal wall can mimic deeper problems. This is more likely if the pain started after heavy lifting, an intense workout, or a sudden twisting movement. The key difference is that muscle pain typically worsens when you tense your core, change positions, or press on the area, and it doesn’t come with fever, bowel changes, or urinary symptoms. It generally improves with rest over a few days to a couple of weeks.
When Left Lower Abdominal Pain Is an Emergency
Some patterns of pain signal something that needs immediate evaluation. You should go to the emergency room if the pain is severe enough to interrupt your ability to function normally, if you’re vomiting repeatedly and can’t keep liquids down, if you’re unable to have a bowel movement and the pain is worsening, or if you’ve had abdominal surgery in the past and this pain feels different from what you’ve experienced before.
Specific red flags that require urgent attention include pain with high fever, blood in your stool or urine, signs of an ectopic pregnancy (pain with vaginal bleeding and dizziness), or pain that came on suddenly and is getting rapidly worse. Even if your pain doesn’t fit neatly into these categories, any abdominal pain that feels significantly different from what you’ve had before, more severe, longer lasting, or paired with new symptoms, is worth getting checked.