Abdominal pain has over 150 known causes, ranging from harmless gas to serious surgical emergencies. In a large study of emergency department visits for abdominal pain, acute gastroenteritis (10.8%) and nonspecific abdominal pain (10.4%) were the two most common diagnoses, followed by gallstones (4.5%), kidney stones (4.3%), diverticulitis (3.8%), and appendicitis (3.8%). Those six conditions alone account for roughly a third of all cases, but what’s causing your pain often depends on exactly where you feel it.
Where the Pain Is Matters
Your abdomen contains dozens of organs packed into a relatively small space. Pain in a specific spot usually points toward whichever organ sits in that region, which is why a doctor’s first question is almost always “where does it hurt?”
Upper right pain most commonly involves the gallbladder (gallstones or gallbladder inflammation), the liver, or a kidney stone on the right side. Upper left pain is more often linked to the stomach, pancreas, spleen, or left kidney. Pain in the center just below the ribs, called the epigastric area, tends to come from the stomach (ulcers, acid reflux, gastritis) or the pancreas, though heart problems can also cause pain here, especially in older adults.
Lower right pain is the classic location for appendicitis, though it can also signal problems with the colon, a kidney stone, or in women, an ovarian cyst or ectopic pregnancy. Lower left pain is the hallmark of diverticulitis, a condition where small pouches in the colon wall become inflamed. Pain around the belly button is often related to early appendicitis, stomach ulcers, or small bowel problems. And pain that’s spread across more than half the abdomen, with no single focal point, usually points toward a stomach virus, gas, constipation, or irritable bowel syndrome.
Digestive Causes
The gastrointestinal tract is by far the most common source of abdominal pain. Gastroenteritis, the stomach flu, tops the list. It’s typically caused by a viral or bacterial infection, produces cramping pain alongside nausea, vomiting, and diarrhea, and resolves on its own within a few days.
Acid reflux (GERD) causes a burning pain in the upper abdomen or chest that worsens after eating or lying down. Peptic ulcers, open sores in the stomach lining or upper small intestine, create a gnawing or burning pain in the upper abdomen that sometimes improves with food and sometimes gets worse. Many ulcers are caused by a bacterial infection with H. pylori, which can be treated with antibiotics.
Gallstones affect the upper right abdomen, often producing intense pain after fatty meals. When a stone blocks the bile duct or the gallbladder becomes inflamed (cholecystitis), the pain can be severe and steady rather than crampy. One useful physical sign: if pressing just below the right rib cage during a deep breath makes you stop mid-inhale because of sharp pain, that’s a classic indicator of gallbladder inflammation.
Diverticulitis typically hits in the lower left abdomen. Small pouches that form in the colon wall over time can become infected or inflamed, causing steady pain, fever, and sometimes changes in bowel habits. It’s more common after age 40. Appendicitis, by contrast, usually starts as vague pain around the belly button that migrates to the lower right abdomen over 12 to 24 hours and gets progressively worse. Tenderness at a point roughly one-third of the way from the right hip bone to the belly button is a well-known diagnostic sign, with a sensitivity of 50% to 94% for appendicitis.
Non-Digestive Causes
Not all abdominal pain starts in the gut. Kidney stones cause sudden, severe pain in the flank or lower abdomen that often radiates to the groin. The pain comes in waves as the stone moves through the urinary tract, and it’s frequently described as one of the most intense pains people experience. Urinary tract infections can also cause lower abdominal pain, particularly a pressure or aching feeling just above the pubic bone, along with burning during urination and frequent urges to go.
In women, several reproductive conditions mimic digestive problems. Ovarian cysts can cause sharp, one-sided lower abdominal pain, especially if a cyst ruptures or twists (ovarian torsion). Ectopic pregnancy, where a fertilized egg implants outside the uterus, causes lower abdominal pain and is a medical emergency if the tissue ruptures. Pelvic inflammatory disease, an infection of the reproductive organs, produces lower abdominal pain with fever and sometimes abnormal discharge. Any sudden, severe lower abdominal pain in a woman of reproductive age warrants prompt evaluation to rule out these conditions.
Less obviously, pneumonia in the lower lungs can cause upper abdominal pain that mimics gallbladder disease. And heart attacks sometimes present as upper abdominal or epigastric pain rather than chest pain, particularly in women, older adults, and people with diabetes.
Chronic and Functional Pain
Some people have abdominal pain that keeps coming back without any visible damage or disease that shows up on tests. These are called functional gastrointestinal disorders, and they’re extremely common.
Irritable bowel syndrome (IBS) causes recurring cramping pain tied to changes in bowel habits, either constipation, diarrhea, or alternating between both. Functional dyspepsia produces pain or discomfort in the upper abdomen connected to eating. Abdominal migraine causes episodes of pain around the belly button along with nausea and sometimes sensitivity to light or sound, and it’s especially common in children. Under current diagnostic guidelines, functional abdominal pain is defined as pain occurring at least four times per month for at least two months that isn’t explained by another condition.
Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is a different category. Unlike functional disorders, IBD involves real, visible inflammation in the gut and tends to cause warning signs like bloody stool, unintentional weight loss, persistent fevers, and in children, slowed growth. A family history of IBD raises suspicion. Crohn’s disease can also cause problems around the anus, including fissures, fistulas, and abscesses.
Vascular Causes
Rarely, abdominal pain comes from problems with blood flow rather than organs themselves. Mesenteric ischemia happens when the arteries supplying the intestines become blocked or narrowed. The acute form comes on suddenly, producing severe pain that seems disproportionate to what the physical exam shows. Nausea, vomiting, and diarrhea are common early on, and it can progress rapidly to bowel death if untreated. The chronic form is more subtle: pain after eating, fear of food, early fullness, and gradual weight loss as people start eating less to avoid the discomfort.
Mesenteric ischemia is most common in people over 60 with heart disease, atrial fibrillation, or atherosclerosis. It’s rare but dangerous, and any severe, sudden abdominal pain in an older adult with cardiovascular risk factors needs urgent evaluation.
Abdominal Pain in Children
Children get abdominal pain frequently, and the vast majority of the time it’s caused by something minor: constipation, gas, a stomach virus, food intolerance, or even anxiety. Colic is the most common cause in infants. In older children, constipation is probably the single most underappreciated cause of recurring belly pain.
More serious causes in children include appendicitis, which presents similarly to adults but can be harder to diagnose in younger kids. Intussusception, where one segment of intestine telescopes into another, typically affects children under three and causes sudden episodes of severe pain, often with a “currant jelly” stool. Swallowed foreign objects, particularly coins, are another pediatric-specific cause that adults don’t have to worry about.
Generalized pain spread across the whole belly in a child usually points to a stomach virus, gas, or constipation. Localized pain in one spot is more concerning and raises the possibility of appendicitis, gallbladder problems, a hernia, or testicular or ovarian torsion.
Signs That Need Urgent Attention
Most abdominal pain is self-limiting and resolves without treatment. But certain features suggest something more dangerous is happening. Severe pain that comes on suddenly, pain with a rigid or board-like abdomen, high fever, bloody vomit or stool, and signs of shock (feeling faint, rapid heart rate, low blood pressure) all point toward conditions that may need emergency treatment.
Low blood pressure combined with abdominal pain is a particularly strong warning sign. In research evaluating clinical red flags, a systolic blood pressure below 100 mmHg in someone with abdominal pain was seven times more likely to indicate a serious surgical condition like appendicitis. Pain that worsens steadily over hours rather than coming and going in waves also tends to signal something that won’t resolve on its own, like a bowel obstruction, organ perforation, or internal bleeding.